Search

Your search keyword '"Yann Girard"' showing total 60 results
Start Over Author "Yann Girard" Topic 01 natural sciences
60 results on '"Yann Girard"'

1. Synthesis and Properties of Nanostructured Tungsten Oxide on Au(111)

Author

Jérôme Lagoute, Vincent Repain, Mahamadou Seydou, Sylvie Rousset, Yann Girard, Philippe Decorse, Cyril Chacon, Mariem Ben Youssef, Rishav Harsh, Philippe Lang, Amandine Bellec, Jean-Yves Piquemal, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Interfaces, Traitements, Organisation et Dynamique des Systèmes (ITODYS (UMR_7086)), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and Université Paris Diderot - Paris 7 (UPD7)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nanostructure, Materials science, Tungsten oxide, [CHIM.MATE]Chemical Sciences/Material chemistry, 02 engineering and technology, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, General Energy, Chemical engineering, 0103 physical sciences, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Physical and Theoretical Chemistry, 010306 general physics, 0210 nano-technology
Abstract

International audience; WO 3 nanostructures have been synthesized on Au(111) through solution processing. Three types of structures have been obtained, reticulated polymeric structures, two dimensional WO 3 (111) and three-dimensional islands. Their electronic properties have been probed by scanning tunneling spectroscopy. The reticulated structure has a featureless spectrum. WO 3 (111) shows n-type semiconducting properties with resonances corresponding to surface states arising from W 5d states. Those oxyde nanostructures are efficiently decoupling the electronic states of molecular adsorbates from the metal substrate.

Published
2020

2. Intraconfigurational Transition due to Surface-Induced Symmetry Breaking in Noncovalently Bonded Molecules

Author

Cyrille Barreteau, Robert Sporken, Rishav Harsh, Yann Girard, Vincent Repain, Alexander Smogunov, Jérôme Lagoute, Cyril Chacon, Frédéric Joucken, Mads Brandbyge, Amandine Bellec, Fei Gao, Sylvie Rousset, Mehdi Bouatou, Yannick J. Dappe, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre de Recherche en Physique de la Matière et du Rayonnement [Namur] (PMR), Université de Namur [Namur] (UNamur), Center for Nanostructured Graphene, Danmarks Tekniske Universitet (DTU), Groupe Modélisation et Théorie (GMT), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Danmarks Tekniske Universitet = Technical University of Denmark (DTU), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay

Subjects
Materials science, Graphene, 02 engineering and technology, Weak interaction, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, law.invention, Atomic orbital, law, Chemical physics, Molecule, General Materials Science, Redistribution (chemistry), Electron configuration, Symmetry breaking, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Physics::Chemical Physics, Physical and Theoretical Chemistry, 0210 nano-technology, Ground state, ComputingMilieux_MISCELLANEOUS
Abstract

The interaction of molecules with surfaces plays a crucial role in the electronic and chemical properties of supported molecules and needs a comprehensive description of interfacial effects. Here, we unveil the effect of the substrate on the electronic configuration of iron porphyrin molecules on Au(111) and graphene, and we provide a physical picture of the molecule-surface interaction. We show that the frontier orbitals derive from different electronic states depending on the substrate. The origin of this difference comes from molecule-substrate orbital selective coupling caused by reduced symmetry and interaction with the substrate. The weak interaction on graphene keeps a ground state configuration close to the gas phase, while the stronger interaction on gold stabilizes another electronic solution. Our findings reveal the origin of the energy redistribution of molecular states for noncovalently bonded molecules on surfaces.

Published
2020

3. Thermal Bistability of an Ultrathin Film of Iron(II) Spin-Crossover Molecules Directly Adsorbed on a Metal Surface

Author

Cristian Enachescu, Yann Girard, Massine Kelai, Philippe Sainctavit, Marie-Laure Boillot, M.-A. Arrio, Arthur Tauzin, Jérôme Lagoute, Sylvie Rousset, Edwige Otero, Talal Mallah, Weibin Li, Vincent Repain, Amandine Bellec, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO), Institut de Chimie du CNRS (INC)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Alexandru Ioan Cuza University of Iasi, University of Iasi, Grant of the Romanian ministry of research, Innovation and Digitization, CNCS/CCCDI-UEFISCDI, project N° PN-III-P4-ID-PCE-2020-1946, European Project: 766726,211587,COSMICS(2017), Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), and SOLEIL Synchrotron, L'Orme des Merisiers, 91198 Gif-sur-Yvette, France

Subjects
Materials science, Absorption spectroscopy, Bistability, 02 engineering and technology, Substrate (electronics), [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010402 general chemistry, 01 natural sciences, Condensed Matter::Materials Science, symbols.namesake, Thermal Bistability, Spin crossover, Monolayer, General Materials Science, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Physical and Theoretical Chemistry, ComputingMilieux_MISCELLANEOUS, Arrhenius equation, Substrate Interaction, Spintronics, Mechanoelastic Model, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, X-ray Absorption Spectroscopy, Spin-Crossover, Chemical physics, symbols, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 0210 nano-technology
Abstract

Spin-crossover molecules are very attractive compounds to realize multifunctional spintronic devices. Understanding their properties when deposited on metals is therefore crucial for their future rational implementation as ultrathin films in such devices. Using X-ray absorption spectroscopy, we study the thermal transition of the spin-crossover compound FeII((3,5-(CH3)2Pz)3BH)2 from submonolayer to multilayers on a Cu(111) substrate. We determine how the residual fraction of high spin molecules at low temperature, as well as the bistability range and the temperature of switching, depends on the layer thickness. The most spectacular effect is the clear opening of a 35 ± 9 K thermal hysteresis loop for a 3.0 ± 0.7 monolayers thick film. To better understand the role played by the substrate and the dimensionality on the thermal bistability, we have performed Monte Carlo Arrhenius simulations in the framework of a mechanoelastic model that include a molecule-substrate interaction. This model reproduces well the main features observed experimentally and can predict how the spin-crossover transition is modified by the thickness and the substrate interaction.

Published
2021

4. Robust magnetic anisotropy of a monolayer of hexacoordinate Fe( ii ) complexes assembled on Cu(111)

Author

Olga Iasco, V. Repain, Cyril Chacon, Massine Kelai, Mihail Atanasov, Régis Guillot, Edwige Otero, Philippe Sainctavit, Marie-Laure Boillot, Luqiong Zhang, Frank Neese, Talal Mallah, Jérôme Lagoute, Eric Rivière, Benjamin Cahier, S. Rousset, Amandine Bellec, Marie-Anne Arrio, Anne-Laure Barra, Yann Girard, Yongfeng Tong, Mathématique et Physique Quantique (MPQ), Centre National de la Recherche Scientifique (CNRS), Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO), Institut de Chimie du CNRS (INC)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Max Planck Institute for Chemistry (MPIC), Max-Planck-Gesellschaft, Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences (BAS), Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Synchrotron SOLEIL (SSOLEIL), Laboratoire national des champs magnétiques intenses - Grenoble (LNCMI-G ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées, Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPC), Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)

Subjects
Tris, Materials science, chemistry.chemical_element, FOS: Physical sciences, 02 engineering and technology, Substrate (electronics), [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010402 general chemistry, 01 natural sciences, Inorganic Chemistry, chemistry.chemical_compound, spin crossover, monolayer, Monolayer, Molecule, [CHIM.COOR]Chemical Sciences/Coordination chemistry, ZFS, Boron, theoretical calculations, Condensed Matter - Materials Science, magnetic anisotropy, XMCD, Fe(II), Ligand, Hexacoordinate, Materials Science (cond-mat.mtrl-sci), [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, 3. Good health, Magnetic anisotropy, Crystallography, chemistry, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 0210 nano-technology
Abstract

International audience; The tris pyrazolyl borate ligand imposes a rigid scaffold around Fe( ii ) ensuring a robust magnetic anisotropy when the molecules assembled as monolayers suffer from the dissymmetric environment of the substrate/vacuum interface.

Published
2021
Full Text
View/download PDF

5. Black Phosphorus for Directed Molecular Assembly with Weak Electronic Coupling

Author

Alexander Smogunov, Cyril Chacon, Mehdi Bouatou, Sylvie Rousset, Rishav Harsh, Vincent Repain, Jérôme Lagoute, Yann Girard, Amandine Bellec, Yannick J. Dappe, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Service de physique de l'état condensé (SPEC - UMR3680), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Mechanical Engineering, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, black phosphorus, 01 natural sciences, Black phosphorus, 0104 chemical sciences, law.invention, Coupling (electronics), Mechanics of Materials, law, Chemical physics, scanning tunneling microscopy, Density functional theory, molecules, Scanning tunneling microscope, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 0210 nano-technology, density functional theory
Abstract

International audience; The combination of two-dimensional materials with organic molecules offers the possibility to obtain low dimensional hybrid materials with tailored properties. Black phosphorus is a monoelemental semiconducting material with a non-planar puckered atomic structure. Here, we study porphyrin molecules on black phosphorus and show that they self-assemble with an epitaxial relationship indicating that the molecule-surface interaction largely dominates the molecule-molecule interaction. The atomic structure of black phosphorus is found to be at the origin of the substrate driven self-assembly. Despite this strong interaction with molecules, the electronic coupling is found to be weak allowing the molecules to maintain the properties of their gas phase, which is the usual behaviour for van der Waals materials. Therefore, the combination of the peculiar puckered structure with the van der Waals nature of black phosphorus provides this material with the ability to interact strongly enough with adsorbed molecules to drive their assembly but weakly enough to keep their electronic properties intact.

Published
2021
Full Text
View/download PDF

6. High density synthesis of topological point defects in graphene on 6H–SiC(000 1 ¯ )

Author

Amandine Bellec, Vincent Repain, Hakim Amara, Sylvain Latil, Quentin Berrahal, Sylvie Rousset, Cyril Chacon, Jérôme Lagoute, Yann Girard, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Laboratoire d'étude des microstructures [Châtillon] (LEM - ONERA - CNRS), Centre National de la Recherche Scientifique (CNRS)-ONERA, Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), and ONERA-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Grain Boundaries, Scanning tunneling spectroscopy, 02 engineering and technology, Growth, Silicon carbide, 010402 general chemistry, 01 natural sciences, Defect engineering, Topological defect, law.invention, chemistry.chemical_compound, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], law, Monolayer, General Materials Science, business.industry, Graphene, Fermi energy, General Chemistry, 021001 nanoscience & nanotechnology, Crystallographic defect, Scanning tunelling microscopy/ spectroscopy, 0104 chemical sciences, chemistry, Density functional theory, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Optoelectronics, 0210 nano-technology, business, Flower formation
Abstract

The control of the physical properties of graphene is a forefront challenge for the development of applications based on this material. Defect engineering is a promising strategy to attain new properties by the insertion of well-defined defects in the carbon lattice. Among the many topological defects of graphene, the one that has the lowest energy per dislocation is a quasi-point-like defect, the so-called Flower Defect (FD). It is generally produced randomly during the graphene synthesis. The deliberate insertion of this defect is promising for the tuning of graphene electronic properties but necessitate to establish a synthesis route allowing to control the formation of flower defects. Here we report a controlled synthesis of graphene with FD using gold as an activator during the graphene synthesis from a 6H–SiC(000 1 ¯ ) silicon carbide wafer. The synthesis consists of a two-step procedure. Creation of a proto-graphene template where one monolayer of gold is evaporated followed by synthesis close to 1200 °C. This leads to a high density of FD, around 10 12 cm - 2 . These results are supported by first-principles calculations showing that gold decreases the flower formation energy by a factor of 2. Scanning tunneling spectroscopy measurements reveal unexpected resonances close to the Fermi energy.

Published
2020

7. Direct Observation of the Reduction of a Molecule on Nitrogen Pairs in Doped Graphene

Author

Jérôme Lagoute, Mehdi Bouatou, Sourav Mondal, Yann Girard, Vincent Repain, Amandine Bellec, Shobhana Narasimhan, Frédéric Joucken, Robert Sporken, Cyril Chacon, Sylvie Rousset, Yannick J. Dappe, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Centre de Recherche en Physique de la Matière et du Rayonnement [Namur] (PMR), Université de Namur [Namur] (UNamur), Groupe Modélisation et Théorie (GMT), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Service de physique de l'état condensé (SPEC - UMR3680), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Bioengineering, 02 engineering and technology, 01 natural sciences, Redox, Atomic units, law.invention, Doped graphene, Charge transfer, law, 0103 physical sciences, Molecule, General Materials Science, Redistribution (chemistry), [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, Scanning tunneling microscopy, ComputingMilieux_MISCELLANEOUS, Dopant, Graphene, Mechanical Engineering, Doping, General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Chemical physics, Scanning tunneling microscope, 0210 nano-technology
Abstract

Incorporating functional atomic sites in graphene is essential for realizing advanced two-dimensional materials. Doping graphene with nitrogen offers the opportunity to tune its chemical activity with significant charge redistribution occurring between molecules and substrate. The necessary atomic scale understanding of how this depends on the spatial distribution of dopants, as well as their positions relative to the molecule, can be provided by scanning tunneling microscopy. Here we show that a noncovalently bonded molecule such as CoPc undergoes a variable charge transfer when placed on N-doped graphene; on a nitrogen pair, it undergoes a redox reaction with an integral charge transfer whereas a lower fractional charge transfer occurs over a single nitrogen. Thus, the charge state of molecules can be tuned by suitably tailoring the conformation of dopant atoms.

Published
2020

8. Control of Dipolar Switches on Graphene by a Local Electric Field

Author

Yannick J. Dappe, Jérôme Lagoute, Yann Girard, Cyril Chacon, Sylvie Rousset, Robert Sporken, César González, Mehdi Bouatou, Amandine Bellec, Vincent Repain, Frédéric Joucken, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Centre de Recherche en Physique de la Matière et du Rayonnement [Namur] (PMR), Université de Namur [Namur] (UNamur), Universidad Autónoma de Madrid (UAM), Groupe Modélisation et Théorie (GMT), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Universidad Autonoma de Madrid (UAM), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Service de physique de l'état condensé (SPEC - UMR3680), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, law.invention, law, Electric field, Molecule, Electronics, Physical and Theoretical Chemistry, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], ComputingMilieux_MISCELLANEOUS, Molecular switch, business.industry, Graphene, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Dipole, General Energy, Optoelectronics, Scanning tunneling microscope, 0210 nano-technology, business, Realization (systems)
Abstract

The realization of molecular electronic devices relies on the ability to perform elementary operations with functional molecules. Molecular switches are established candidates to realize basic electronic functions and data storage. Macrocyclic molecules such as phthalocyanines and their derivatives provide a family of compounds that can be switched by external stimuli between two stable states. Using scanning tunneling microscopy, we investigated tin phthalocyanine on graphene. We show that these molecules can be reversibly switched between two states and that the interaction of their electric dipole with a local electric field drives the switching yield and direction. The control at the single-molecule level of the molecular conformation in a bidimensional lattice is then used to achieve high-density data storage.

Published
2020

9. Selective control of molecule charge state on graphene using tip-induced electric field and nitrogen doping

Author

Sylvie Rousset, Van Dong Pham, Shobhana Narasimhan, Yann Girard, Amandine Bellec, Yannick J. Dappe, Mario Pelaez-Fernandez, Cyril Chacon, Vincent Repain, Sukanya Ghosh, Robert Sporken, Jérôme Lagoute, Frédéric Joucken, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Paul-Drude-Institut für Festkörperelektronik (PDI), Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Abdus Salam International Centre for Theoretical Physics [Trieste] (ICTP), Centre de Recherche en Physique de la Matière et du Rayonnement [Namur] (PMR), Université de Namur [Namur] (UNamur), Laboratoire de Photophysique Moléculaire (PPM), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Groupe Modélisation et Théorie (GMT), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Paul-Drude-Institut für Festkörperelektronik, Université de Namur [Namur], Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay

Subjects
Materials science, Ab initio, 02 engineering and technology, 01 natural sciences, law.invention, lcsh:Chemistry, law, Ab initio quantum chemistry methods, Electric field, 0103 physical sciences, Physics::Atomic and Molecular Clusters, lcsh:TA401-492, [CHIM]Chemical Sciences, General Materials Science, Physics::Chemical Physics, 010306 general physics, Graphene, Mechanical Engineering, Charge (physics), General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Dipole, lcsh:QD1-999, Mechanics of Materials, Chemical physics, Density functional theory, lcsh:Materials of engineering and construction. Mechanics of materials, 0210 nano-technology, Voltage
Abstract

The combination of graphene with molecules offers promising opportunities to achieve new functionalities. In these hybrid structures, interfacial charge transfer plays a key role in the electronic properties and thus has to be understood and mastered. Using scanning tunneling microscopy and ab initio density functional theory calculations, we show that combining nitrogen doping of graphene with an electric field allows for a selective control of the charge state in a molecular layer on graphene. On pristine graphene, the local gating applied by the tip induces a shift of the molecular levels of adsorbed molecules and can be used to control their charge state. Ab initio calculations show that under the application of an electric field, the hybrid molecule/graphene system behaves like an electrostatic dipole with opposite charges in the molecule and graphene sub-units that are found to be proportional to the electric field amplitude, which thereby controls the charge transfer. When local gating is combined with nitrogen doping of graphene, the charging voltage of molecules on nitrogen is greatly lowered. Consequently, applying the proper electric field allows one to obtain a molecular layer with a mixed charge state, where a selective reduction is performed on single molecules at nitrogen sites.

Published
2019

10. Properties of Functionalized Carbon Nanotubes and Their Interaction with a Metallic Substrate Investigated by Scanning Tunneling Microscopy

Author

Maria Cristina dos Santos, Jérôme Lagoute, Van Dong Pham, Cyril Chacon, Jean-Sébastien Lauret, Mauricio Terrones, Stéphane Campidelli, Amandine Bellec, Yann Girard, Vincent Repain, Sylvie Rousset, Christophe Voisin, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Innovation en Chimie des Surfaces et NanoSciences (LICSEN), Nanosciences et Innovation pour les Matériaux, la Biomédecine et l'Energie (ex SIS2M) (NIMBE UMR 3685), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire Aimé Cotton (LAC), École normale supérieure - Cachan (ENS Cachan)-Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Pierre Aigrain (LPA), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Center for 2-Dimensional and Layered Materials, Pennsylvania State University (Penn State), Penn State System-Penn State System, Institute of Carbon Science and Technology, Shinshu University [Nagano], Groningen Biomolecular Sciences and Biotechnology Institute & Zernike Institute for Advanced Materials, University of Groningen [Groningen], Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-École normale supérieure - Cachan (ENS Cachan), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Zernike Institute for Advanced Materials, Brazilian Agency FAPESP, ANR-10-LABX-0096,SEAM,Science and Engineering for Advanced Materials and devices(2010), Laboratoire Innovation en Chimie des Surfaces et NanoSciences (LICSEN UMR 3685), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), ANR-11-LABX-086 - ANR-11-IDEX-05-02,LabEx SEAM,Science and Engineering for Advanced Materials and devices, Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and Photophysics and OptoElectronics

Subjects
Nanotube, Materials science, GRAPHITE, PHASE, Selective chemistry of single-walled nanotubes, Mechanical properties of carbon nanotubes, Nanotechnology, 02 engineering and technology, Carbon nanotube, 010402 general chemistry, 01 natural sciences, law.invention, Condensed Matter::Materials Science, MOLECULES, NONCOVALENT FUNCTIONALIZATION, law, ALKANE, Physical and Theoretical Chemistry, [PHYS]Physics [physics], Local density of states, ATOMIC-STRUCTURE, RECOGNITION, [CHIM.MATE]Chemical Sciences/Material chemistry, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Optical properties of carbon nanotubes, General Energy, Carbon nanobud, PORPHYRIN, TRANSISTORS, BIOSENSORS, Scanning tunneling microscope, 0210 nano-technology
Abstract

International audience; Non-covalent functionalization of carbon nanotubes (CNTs) allows the combination of the remarkable physical properties of these one-dimensional systems with the properties of the functional molecules and, at the same time, modifies the physico-chemical properties of nanotubes for specific applications. The use of functionalized carbon nanotubes in electronics often requires the deposition of the nanotubes on a substrate, and eventually an annealing step, which can modify their properties due to molecule-surface interactions. Using scanning tunneling microscopy/spectroscopy (STM/STS) and classical molecular dynamics (MD) simulations we studied the physical properties of carbon nanotubes functionalized with porphyrin derivatives and discuss the effect of physisorption and sample annealing on the nanotube surface. The results reveal that the functionalized parts exhibit non periodic structure with a significant modification of the local density of states. The coverage degree, can be estimated from STM images. When the sample is annealed, STM data clearly show an unwrapping of the functionalizing species leading to a lowering of the coverage degree. In addition, periodic structures were observed that correspond to the surfactants originally present in the CNT sample, revealing that the surfactants are still present in such functionalized nanotubes. These results provide information on the structure and properties of polymer functionalized nanotubes and the effect of substrate interaction and sample annealing that can markedly modify the structure and properties of the functionalized nanotubes.

Published
2017
Full Text
View/download PDF

11. Controlling Hydrogen-Transfer Rate in Molecules on Graphene by Tunable Molecular Orbital Levels

Author

Jérôme Lagoute, Amandine Bellec, Sylvie Rousset, Yann Girard, Alexander Smogunov, Rishav Harsh, Vincent Repain, Robert Sporken, Frédéric Joucken, Cyril Chacon, Yannick J. Dappe, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre de Recherche en Physique de la Matière et du Rayonnement [Namur] (PMR), Université de Namur [Namur] (UNamur), Laboratoire de Photophysique Moléculaire (PPM), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Groupe Modélisation et Théorie (GMT), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and Université de Namur [Namur]

Subjects
Molecular switch, Materials science, Dopant, Graphene, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, law.invention, law, Chemical physics, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], Molecule, General Materials Science, Molecular orbital, Physical and Theoretical Chemistry, Scanning tunneling microscope, 0210 nano-technology, Excitation, Quantum tunnelling
Abstract

International audience; Molecular switches are building blocks of potential interest to store binary information, especially when they can be organized in periodic lattices. Among the variety of possible systems, switches based on hydrogen transfer are of special importance because they allow the switching operation to occur without severe conformational change that may interfere with neighboring molecular units. We have studied the excitation process of hydrogen transfer inside porphyrin molecules assembled on a graphene surface, using a low-temperature scanning tunneling microscope. We show that this hydrogen transfer is induced by an electronic resonant tunneling process through the molecular orbitals. Using nitrogen doping of graphene, we tune the rate of hydrogen transfer by shifting the molecular orbital energies owing to the charge transfer at nitrogen dopant sites in the graphene lattice. The control of the switching process allows the storage of information inside a molecular lattice, which is demonstrated by writing an artificial pattern inside a molecular island.

Published
2019

12. Importance of Epitaxial Strain at a Spin-Crossover Molecule–Metal Interface

Author

Yannick J. Dappe, Talal Mallah, Cynthia Fourmental, Jérôme Lagoute, Cristian Enachescu, Cyrille Barreteau, Sourav Mondal, Shobhana Narasimhan, Marie-Laure Boillot, Rajdeep Banerjee, Sylvie Rousset, Alessandro Coati, Amandine Bellec, Yann Girard, Vincent Repain, Cyril Chacon, Alexander Smogunov, Yves Garreau, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Laboratoire de chimie inorganique (LCI), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Department of Solid State and Theoretical Physics, Alexandru Ioan Cuza University of Iași [Romania], Groupe Modélisation et Théorie (GMT), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Theoretical Sciences Unit, European Project: 766726,211587,COSMICS(2017), Université Paris-Sud - Paris 11 (UP11)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay

Subjects
Diffraction, Materials science, Spin states, Spintronics, 02 engineering and technology, Substrate (electronics), 010402 general chemistry, 021001 nanoscience & nanotechnology, Epitaxy, 01 natural sciences, 0104 chemical sciences, Chemical physics, Spin crossover, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Molecule, General Materials Science, Physical and Theoretical Chemistry, 0210 nano-technology, Spin-½
Abstract

International audience; Spin-crossover molecules are very appealing for use in multifunctional spintronic devices because of their ability to switch between high-spin and low-spin states with external stimuli such as voltage and light. In actual devices, the molecules are deposited on a substrate, which can modify their properties. However, surprisingly little is known about such molecule–substrate effects. Here we show for the first time, by grazing incidence X-ray diffraction, that an FeII spin-crossover molecular layer displays a well-defined epitaxial relationship with a metal substrate. Then we show, by both density functional calculations and a mechanoelastic model, that the resulting epitaxial strain and the related internal pressure can induce a partial spin conversion at low temperatures, which has indeed been observed experimentally. Our results emphasize the importance of substrate-induced spin state transitions and raise the possibility of exploiting them.

Published
2019

13. Experimental and theoretical investigations of magnetic anisotropy and magnetic hardening at molecule/ferromagnet interfaces

Author

C. Fourmental, Cyrille Barreteau, Yann Girard, L. Le Laurent, Jérôme Lagoute, Sylvie Rousset, Kaushik Bairagi, Cyril Chacon, Alexander Smogunov, Vincent Repain, Amandine Bellec, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Groupe Modélisation et Théorie (GMT), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Service de physique de l'état condensé (SPEC - UMR3680), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), European Project: 766726,211587,COSMICS(2017), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, LIttoral ENvironnement et Sociétés - UMR 7266 (LIENSs), and Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS]Physics [physics], Kerr effect, Materials science, Condensed matter physics, Magnetism, 02 engineering and technology, Coercivity, 021001 nanoscience & nanotechnology, 01 natural sciences, Condensed Matter::Materials Science, Magnetization, Magnetic anisotropy, Ferromagnetism, Ab initio quantum chemistry methods, Magnet, 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 010306 general physics, 0210 nano-technology
Abstract

We measure by means of in situ magneto-optical Kerr effect the magnetism of ultrathin magnetic films supported on gold and platinum during the capping with molecular layers. We observe both for ${\mathrm{C}}_{60}$ and ${\mathrm{Alq}}_{3}$ molecules deposited on Co films an enhancement of the out-of-plane magnetic anisotropy, leading to a magnetic hardening for out-of-plane magnetization. Surprisingly, the amplitude of this hardening depends strongly on the underlying substrate. While we find an increase of the coercive field around 100% for Co/Au(111), it can reach almost 600% on Co/Pt(111). Those results are discussed by using both tight-binding and ab initio calculations. It is shown on the case of ${\mathrm{C}}_{60}$ that both the adsorption geometry and the strain in the magnetic layer can be key ingredients to predict the quantitative change of magnetic anisotropy induced by the interface between a magnetic material and a molecular layer. On the contrary, the crystalline stacking of the Co has a minor influence.

Published
2018

14. Temperature-, Light-, and Soft X-ray-Induced Spin Crossover in a Single Layer of Fe II -Pyrazolylborate Molecules in Direct Contact with Gold

Author

Cynthia Fourmental, Talal Mallah, Olga Iasco, Marie-Laure Boillot, Jérôme Lagoute, Fadi Choueikani, Vincent Repain, Edwige Otero, Philippe Sainctavit, Kaushik Bairagi, Amandine Bellec, Philippe Ohresser, Yann Girard, Cyril Chacon, Sylvie Rousset, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Photophysique Moléculaire (PPM), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Multimatériaux et Interfaces (LMI), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Groupe de Physique des Solides (GPS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Unité de Nutrition Humaine - Clermont Auvergne (UNH), Institut National de la Recherche Agronomique (INRA)-Université Clermont Auvergne (UCA), Dispositifs et Instrumentation en Optoélectronique et micro-ondes (DIOM), Université Jean Monnet [Saint-Étienne] (UJM), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Université de Lyon-Université de Lyon-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Unité de Nutrition Humaine (UNH), Institut National de la Recherche Agronomique (INRA)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020]), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Université Paris-Sud - Paris 11 (UP11)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC), and Université Jean Monnet - Saint-Étienne (UJM)

Subjects
Materials science, Spin states, Absorption spectroscopy, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, law.invention, law, Spin crossover, Phase (matter), Monolayer, Molecule, Physical and Theoretical Chemistry, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], ComputingMilieux_MISCELLANEOUS, [PHYS]Physics [physics], Spintronics, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, General Energy, Chemical physics, Condensed Matter::Strongly Correlated Electrons, Scanning tunneling microscope, 0210 nano-technology
Abstract

International audience; Understanding the properties of spin-crossover molecules in direct contact with metals is crucial for their future integration in electronic and spintronic devices. By X-ray absorption spectroscopy, we investigate the properties of Fe-II((3,5-(CH3)(2)Pz)(3)BH)(2) molecules in the form of monolayer islands on a metallic substrate, namely, Au(111). We demonstrate that the spin crossover transition can be thermally induced from the high spin state to a mixed spin state phase containing one-third of high-spin state and two-thirds of low-spin-state molecules in agreement with previous work by scanning tunneling microscopy. In addition, at 4.4 K, the spin crossover from the low spin state to the high spin state can also be induced by X-ray and by light excitations.

Published
2017

15. Tuning the Electronic and Dynamical Properties of a Molecule by Atom Trapping Chemistry

Author

Jérôme Lagoute, Enrique Abad, Van Dong Pham, Sylvie Rousset, Amandine Bellec, Alexander Smogunov, Yannick J. Dappe, Cyril Chacon, Yann Girard, Vincent Repain, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Departamento de Física Teórica de la Materia Condensada [Madrid] (DFTMC), Facultad de Ciencas [Madrid], Universidad Autonoma de Madrid (UAM)-Universidad Autonoma de Madrid (UAM), Groupe Modélisation et Théorie (GMT), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), ANR-10-LABX-0096,SEAM,Science and Engineering for Advanced Materials and devices(2010), Departamento de Fisica Teorica de la Materia Condensada, Universidad Autonoma de Madrid (UAM), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Universidad Autónoma de Madrid (UAM)-Universidad Autónoma de Madrid (UAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and ANR-11-LABX-086 - ANR-11-IDEX-05-02,LabEx SEAM,Science and Engineering for Advanced Materials and devices

Subjects
General Physics and Astronomy, 02 engineering and technology, Trapping, 010402 general chemistry, 01 natural sciences, law.invention, Metal, chemistry.chemical_compound, single-molecule manipulation, Deprotonation, molecular rotor, law, Computational chemistry, Tetraphenylporphyrin, Molecule, General Materials Science, density functional theory, Pyrrole, [PHYS]Physics [physics], General Engineering, 021001 nanoscience & nanotechnology, 0104 chemical sciences, chemistry, Chemical physics, visual_art, visual_art.visual_art_medium, scanning tunneling microscopy, Density functional theory, Scanning tunneling microscope, 0210 nano-technology
Abstract

International audience; The ability to trap adatoms with an organic molecule on a surface has been used to obtain a range of molecular functionalities controlled by the choice of the molecular trapping site and local deprotonation. The tetraphenylporphyrin molecule used in this study contains three types of trapping sites: two carbon rings (phenyl and pyrrole) and the center of a macrocycle. Catching a gold adatom on the carbon rings leads to an electronic doping of the molecule, whereas trapping the adatom at the macrocycle center with single deprotonation leads to a molecular rotor and a second deprotonation leads to a molecular jumper. We call " atom trapping chemistry " the control of the structure, electronic, and dynamical properties of a molecule achieved by trapping metallic atoms with a molecule on a surface. In addition to the examples previously described, we show that more complex structures can be envisaged.

Published
2017

16. Coupled study by TEM/EELS and STM/STS of electronic properties of C- and CNx-nanotubes

Author

Annick Loiseau, Cyril Chacon, V. Repain, Raul Arenal, Yann Girard, Hong Lin, Jean-Sébastien Lauret, Jérôme Lagoute, S. Rousset, François Ducastelle, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'étude des microstructures [Châtillon] (LEM - ONERA - CNRS), Centre National de la Recherche Scientifique (CNRS)-ONERA, Laboratoire de Photonique Quantique et Moléculaire (LPQM), École normale supérieure - Cachan (ENS Cachan)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Laboratorio de microscopias avanzadas (LMA), University of Zaragoza - Universidad de Zaragoza [Zaragoza], Grant of CNano IdF 'SAMBA', ONERA-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-CentraleSupélec-École normale supérieure - Cachan (ENS Cachan)

Subjects
Materials science, Scanning tunneling spectroscopy, Selective chemistry of single-walled nanotubes, Carbon nanotubes, Energy Engineering and Power Technology, FOS: Physical sciences, Nanotechnology, 02 engineering and technology, Carbon nanotube, 01 natural sciences, law.invention, Condensed Matter::Materials Science, law, 0103 physical sciences, Molecular orbital, 010306 general physics, Scanning Tunneling Spectroscopy, Condensed Matter - Materials Science, Electron energy loss spectroscopy, General Engineering, Molecular electronics, Materials Science (cond-mat.mtrl-sci), 021001 nanoscience & nanotechnology, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, Optical properties of carbon nanotubes, 73.22.Dj, 68.37.Ef, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Scanning tunneling microscope, 0210 nano-technology
Abstract

Carbon nanotubes are the focus of considerable research efforts due to their fascinating physical properties. They provide an excellent model system for the study of one-dimensional materials and molecular electronics. The chirality of nanotubes can lead to very different electronic behaviour, either metallic or semiconducting. Their electronic spectrum consists of a series of Van Hove singularities defining a bandgap for semiconducting tubes and molecular orbitals at the corresponding energies. A promising way to tune the nanotubes electronic properties for future applications is to use doping by heteroatoms. Here we report on the experimental investigation of the role of many-body interactions in nanotube bandgaps, the visualization in direct space of the molecular orbitals of nanotubes and the properties of nitrogen doped nanotubes using scanning tunneling microscopy and transmission electron microscopy as well as electron energy loss spectroscopy.

Published
2017

17. Electronic Interaction between Nitrogen-Doped Graphene and Porphyrin Molecules

Author

Cyril Chacon, S. Rousset, Yann Girard, Van Dong Pham, Amandine Bellec, Ouafi Mouhoub, Frédéric Joucken, V. Repain, Jérôme Lagoute, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'étude des microstructures [Châtillon] (LEM - ONERA - CNRS), ONERA-Centre National de la Recherche Scientifique (CNRS), Mathématique et Physique Quantique (MPQ), Centre National de la Recherche Scientifique (CNRS), Centre de Recherche en Physique de la Matière et du Rayonnement [Namur] (PMR), Université de Namur [Namur] (UNamur), Knoop, Martina, and Université de Namur [Namur]

Subjects
Materials science, Scanning tunneling spectroscopy, General Physics and Astronomy, tetraphenylporphyrins, Nanotechnology, 02 engineering and technology, Electronic structure, 010402 general chemistry, 01 natural sciences, [PHYS] Physics [physics], law.invention, chemistry.chemical_compound, law, Tetraphenylporphyrin, Molecule, General Materials Science, [PHYS]Physics [physics], Graphene, graphene, charge transfer, nitrogen doping, General Engineering, self-assembly, 021001 nanoscience & nanotechnology, Porphyrin, 0104 chemical sciences, chemistry, scanning tunneling microscopy, scanning tunneling spectroscopy, 0210 nano-technology, Bilayer graphene, Graphene nanoribbons
Abstract

The chemical doping of graphene is a promising route to improve the performances of graphene-based devices through enhanced chemical reactivity, catalytic activity, or transport characteristics. Understanding the interaction of molecules with doped graphene at the atomic scale is therefore a leading challenge to be overcome for the development of graphene-based electronics and sensors. Here, we use scanning tunneling microscopy and spectroscopy to study the electronic interaction of pristine and nitrogen-doped graphene with self-assembled tetraphenylporphyrin molecules. We provide an extensive measurement of the electronic structure of single porphyrins on Au(111), thus revealing an electronic decoupling effect of the porphyrins adsorbed on graphene. A tip-induced switching of the inner hydrogen atoms of porphyrins, first identified on Au(111), is observed on graphene, allowing the identification of the molecular conformation of porphyrins in the self-assembled molecular layer. On nitrogen-doped graphene, a local modification of the charge transfer around the nitrogen sites is evidenced via a downshift of the energies of the molecular elecronic states. These data show how the presence of nitrogen atoms in the graphene network modifies the electronic interaction of organic molecules with graphene. These results provide a basic understanding for the exploitation of doped graphene in molecular sensors or nanoelectronics.

Published
2014

18. Order-disorder phase transition inAu2Feon Ru(0001)

Author

Alessandro Coati, Yann Girard, Jérôme Lagoute, Amandine Bellec, Sylvie Rousset, Yves Garreau, Vincent Repain, J.-B. Marie, and Cyril Chacon

Subjects
Diffraction, Phase transition, Materials science, Condensed matter physics, Alloy, Order (ring theory), 02 engineering and technology, engineering.material, 021001 nanoscience & nanotechnology, Epitaxy, 01 natural sciences, law.invention, law, 0103 physical sciences, engineering, Scanning tunneling microscope, 010306 general physics, 0210 nano-technology, Bimetallic strip, Solid solution
Abstract

Order-disorder transition of the epitaxial surface alloy of bulk immiscible elements ${\mathrm{Au}}_{1\ensuremath{-}x}{\mathrm{Fe}}_{x}$ on Ru(0001) is studied using complementary experiments of scanning tunneling microscopy and grazing incidence x-ray diffraction. For $x\ensuremath{\simeq}1/3$, we evidence an apparent continuous transition towards disorder with increasing temperature from 550 to 700 K. An ordered ${\mathrm{Au}}_{2}\mathrm{Fe}$ two-dimensional alloy is found to be composed of nanometer size domains of the three variants that switch to a two-dimensional solid solution with temperature. A two-levels model is developed to analyze those results which conducts to interpret this phase transition as the result of an order-disorder transition within two dimensional uncorrelated grains, or domains, with nearly fixed size. This system is a good candidate in order to study two-dimensional phase transitions of surface alloy, a largely unexplored domain but crucial to understanding thermal stability of bimetallic nanoparticles.

Published
2016

19. Correction to Temperature-, Light-, and Soft X-ray-Induced Spin Crossover in a Single Layer of FeII-Pyrazolylborate Molecules in Direct Contact with Gold

Author

Kaushik Bairagi, Amandine Bellec, Cynthia Fourmental, Yongfeng Tong, Olga Iasco, Jérôme Lagoute, Cyril Chacon, Yann Girard, Sylvie Rousset, Fadi Choueikani, Edwige Otero, Philippe Ohresser, Philippe Sainctavit, Marie-Laure Boillot, Talal Mallah, and Vincent Repain

Subjects
General Energy, 010405 organic chemistry, Physical and Theoretical Chemistry, 010402 general chemistry, 01 natural sciences, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials
Published
2018

20. Growth of Bi on Cu(111): Alloying and dealloying transitions

Author

S. Rousset, Yann Girard, Jérôme Lagoute, V. Repain, G. de Abreu, Cyril Chacon, Département Mécanismes d'Accidents (INRETS/MA), Institut National de Recherche sur les Transports et leur Sécurité (INRETS), Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), and Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Alloy, chemistry.chemical_element, 02 engineering and technology, engineering.material, 01 natural sciences, Surface alloy, Overlayer, law.invention, Bismuth, Adsorption, Transition metal, law, 0103 physical sciences, Monolayer, Materials Chemistry, Scanning tunneling microscopy, 010306 general physics, [PHYS]Physics [physics], Condensed matter physics, Surfaces and Interfaces, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Copper, Surfaces, Coatings and Films, Dealloying, Crystallography, chemistry, engineering, Scanning tunneling microscope, 0210 nano-technology
Abstract

We report on the observation of surface alloying and dealloying transitions during the submonolayer growth of Bi on the Cu(111) surface. In-situ scanning tunneling microscopy (STM) analysis reveals that at low coverage, and for quasi thermodynamical equilibrium, embedded Bi atoms are randomly distributed within the first Cu layer. Near the ideal coverage of 1/3, we observe an ordered BiCu2 substitutional surface alloy. Between 1/3 and 1/2 monolayer a dealloying process takes place where the surface alloy coexists with two different domains of dense Bi overlayer. In order to understand the mechanisms behind this process, the ordered alloy has been used as a template for subsequent Bi adsorption. An apparently etched surface develops during deposition and using STM image analysis, we propose that this growth mode is accompanied by a large Bi and Cu atoms redistribution inside the surface alloy. (C) 2013 Elsevier B.V. All rights reserved.

Published
2013

21. Symmetry-selected spin-split hybrid states inC60/ferromagneticinterfaces

Author

C. Chacon, Cyrille Barreteau, Sylvie Rousset, Jérôme Lagoute, Seiji Leo Kawahara, Alexander Smogunov, V. Repain, Dongzhe Li, and Yann Girard

Subjects
Materials science, Condensed matter physics, Spin polarization, Spintronics, Condensed Matter::Other, Orbital hybridisation, Scanning tunneling spectroscopy, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Orientation (vector space), Condensed Matter::Materials Science, Ferromagnetism, 0103 physical sciences, Molecular orbital, 010306 general physics, 0210 nano-technology, Spin (physics)
Abstract

The understanding of orbital hybridization and spin polarization at the organic-ferromagnetic interface is essential in the search for efficient hybrid spintronic devices. Here, using first-principles calculations, we report a systematic study of spin-split hybrid states of ${\mathrm{C}}_{60}$ deposited on various ferromagnetic surfaces: bcc-Cr(001), bcc-Fe(001), bcc-Co(001), fcc-Co(001), and hcp-Co(0001). We show that the adsorption geometry of the molecule with respect to the surface crystallographic orientation of the magnetic substrate as well as the strength of the interaction play a crucial role in the spin polarization of the hybrid orbitals. We find that a large spin polarization in vacuum above the buckyball can only be achieved if the molecule is adsorbed upon a bcc-(001) surface by its pentagonal ring. Therefore, bcc-Cr(001), bcc-Fe(001), and bcc-Co(001) are the optimal candidates. Spin-polarized scanning tunneling spectroscopy measurements on single ${\mathrm{C}}_{60}$ adsorbed on Cr(001) and Co/Pt(111) also confirm that the symmetry both of the substrate and of the molecular conformation has a strong influence on the induced spin polarization. Our finding may give valuable insights for further engineering of spin filtering devices through single molecular orbitals.

Published
2016

22. Control of Molecule-Metal Interaction by Hydrogen Manipulation in an Organic Molecule

Author

Yann Girard, Yannick J. Dappe, Vincent Repain, Van Dong Pham, Amandine Bellec, Jérôme Lagoute, Alexander Smogunov, Sylvie Rousset, Cyril Chacon, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Groupe Modélisation et Théorie (GMT), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), V.R. thanks the Institut Universitaire de France for support.The calculations have been performed using HPC computation resources from GENCI-[TGCC] (Grant 2016097416)., ANR-11-LABX-086 - ANR-11-IDEX-05-02,LabEx SEAM,Science and Engineering for Advanced Materials and devices, The calculations have been performed using HPC computation resources from GENCI-[TGCC] (Grant 2016097416)., ANR-10-LABX-0096,SEAM,Science and Engineering for Advanced Materials and devices(2010), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay

Subjects
Hydrogen, chemistry.chemical_element, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Molecular conformation, law.invention, Metal, ATOMS, chemistry.chemical_compound, Computational chemistry, Ab initio quantum chemistry methods, law, Molecule, General Materials Science, Physical and Theoretical Chemistry, Wave function, PORPHYRIN MOLECULES, AU(111), [PHYS]Physics [physics], Chemistry, SCANNING-TUNNELING-MICROSCOPY, 021001 nanoscience & nanotechnology, Porphyrin, 0104 chemical sciences, ROOM-TEMPERATURE, SINGLE, visual_art, visual_art.visual_art_medium, Scanning tunneling microscope, 0210 nano-technology
Abstract

International audience; Free-base porphyrin molecules offer appealing options to tune the interaction with their environment via the manipulation of their inner hydrogen atoms and molecular conformation. Using scanning tunneling microscopy we show, through a systematic study, that the molecular conformation, electronic gap, wave function, and molecule-substrate interaction are modified by hydrogen switch or removal. Experimental results in combination with ab initio calculations provide an understanding of the underlying physical process.

Published
2016

23. Molecular-scale dynamics of light-induced spin cross-over in a two-dimensional layer

Author

Jérôme Lagoute, Cyril Chacon, Kaushik Bairagi, Cyrille Barreteau, Alexey Kartsev, Olga Iasco, Talal Mallah, Frédéric Miserque, Alexander Smogunov, Dongzhe Li, Yannick J. Dappe, Amandine Bellec, Yann Girard, Vincent Repain, Marie-Laure Boillot, Sylvie Rousset, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Groupe Modélisation et Théorie (GMT), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude de la Corrosion Aqueuse (LECA), Service de la Corrosion et du Comportement des Matériaux dans leur Environnement (SCCME), Département de Physico-Chimie (DPC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Physico-Chimie (DPC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction de l'Energie Nucléaire (CEA-DEN), Université Paris-Sud - Paris 11 (UP11)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)

Subjects
Materials science, Spin states, Science, General Physics and Astronomy, Nanotechnology, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, General Biochemistry, Genetics and Molecular Biology, Article, Ab initio quantum chemistry methods, Quantum tunnelling, Spin-½, спиновые состояния, [PHYS]Physics [physics], Multidisciplinary, Spintronics, Spin engineering, General Chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Chemical physics, Spinplasmonics, Condensed Matter::Strongly Correlated Electrons, 0210 nano-technology, спин, Nanomechanics
Abstract

Spin cross-over molecules show the unique ability to switch between two spin states when submitted to external stimuli such as temperature, light or voltage. If controlled at the molecular scale, such switches would be of great interest for the development of genuine molecular devices in spintronics, sensing and for nanomechanics. Unfortunately, up to now, little is known on the behaviour of spin cross-over molecules organized in two dimensions and their ability to show cooperative transformation. Here we demonstrate that a combination of scanning tunnelling microscopy measurements and ab initio calculations allows discriminating unambiguously between both states by local vibrational spectroscopy. We also show that a single layer of spin cross-over molecules in contact with a metallic surface displays light-induced collective processes between two ordered mixed spin-state phases with two distinct timescale dynamics. These results open a way to molecular scale control of two-dimensional spin cross-over layers., Spin crossover molecules may find applications in ultimately small magnetic devices, given the sensitivity of their spin-states to external stimuli. Here, the authors show a light-induced transition between two ordered dynamic phases in two-dimensional spin crossover layers on a metallic surface.

Published
2016

24. Quasi unidimensional growth of Co nanostructures on a strained Au(111) surface

Author

Yann Girard, S. Rousset, Paolo Campiglio, Olivier Fruchart, Jérôme Lagoute, V. Repain, Cyril Chacon, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Micro et NanoMagnétisme (MNM), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), ANR-05-NANO-0073,VERNANOMAG,Versatilité de réseaux auto-organisés de nanostructures et matériaux magnétiques : fabrication et fonctionnalités(2005), MNM - Micro et NanoMagnétisme, Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), ANR-NANO-018-04, ANR-05-NANO-073,ANR-NANO-018-04, and ANR-05-NANO-073

Subjects
Surface diusion, Materials science, Nanostructure, Diffusion, Nucleation, chemistry.chemical_element, 02 engineering and technology, 01 natural sciences, law.invention, Low index single crystal surfaces, Metal-metal magnetic thin lm structures, law, 0103 physical sciences, Materials Chemistry, Deposition (phase transition), Scanning tunneling microscopy, 010306 general physics, Surface diffusion, Self-assembly, Cobalt, Surfaces and Interfaces, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 68.55.-a, Surfaces, Coatings and Films, Crystallography, chemistry, Chemical engineering, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Scanning tunneling microscope, 0210 nano-technology, Platinum
Abstract

International audience; We investigated to which extent a uniaxially-strained Au(111) surface, thereby displaying linear reconstructions, may be used as a template for the growth of elongated nanostructures. Cobalt has been used as a deposition material, and two routes have been followed satisfactorily. The rst one consists in the control of diusion through the temperature of deposition. The second one consists in a rst step of platinum seeding in the reconstruction, followed by cobalt deposition with nucleation on the platinum seeds.

Published
2011

25. Charge transfer and electronic doping in nitrogen-doped graphene

Author

A. Taleb-Ibrahimi, Sylvie Rousset, Antonio Tejeda, Frédéric Joucken, Patrick Le Fèvre, Amandine Bellec, Cyril Chacon, François Ducastelle, Edward H. Conrad, Hakim Amara, Jacques Ghijsen, Jérôme Lagoute, Robert Sporken, Yann Girard, Vincent Repain, Yann Tison, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), CASSIOPEE, Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Unité mixte de physique CNRS/Thales (UMPhy CNRS/THALES), THALES [France]-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS), Groupe de Physique des Solides (GPS), Laboratoire Francis PERRIN (LFP - URA 2453), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), ONERA - The French Aerospace Lab [Châtillon], ONERA-Université Paris Saclay (COmUE), Centre National de la Recherche Scientifique (CNRS)-THALES, Unité Mixte de Physique (UNIVERSITE PARIS SUD), Université Paris-Sud - Paris 11 (UP11), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), and ONERA

Subjects
Multidisciplinary, Materials science, Dopant, Graphene, Binding energy, Doping, 02 engineering and technology, Electronic structure, 021001 nanoscience & nanotechnology, Bioinformatics, 01 natural sciences, Article, law.invention, Condensed Matter::Materials Science, X-ray photoelectron spectroscopy, law, Chemical physics, Condensed Matter::Superconductivity, 0103 physical sciences, Physics::Atomic and Molecular Clusters, [CHIM]Chemical Sciences, Scanning tunneling microscope, 010306 general physics, 0210 nano-technology, Spectroscopy
Abstract

Understanding the modification of the graphene’s electronic structure upon doping is crucial for enlarging its potential applications. We present a study of nitrogen-doped graphene samples on SiC(000"Equation missing") combining angle-resolved photoelectron spectroscopy, scanning tunneling microscopy and spectroscopy and X-ray photoelectron spectroscopy (XPS). The comparison between tunneling and angle-resolved photoelectron spectra reveals the spatial inhomogeneity of the Dirac energy shift and that a phonon correction has to be applied to the tunneling measurements. XPS data demonstrate the dependence of the N 1s binding energy of graphitic nitrogen on the nitrogen concentration. The measure of the Dirac energy for different nitrogen concentrations reveals that the ratio usually computed between the excess charge brought by the dopants and the dopants’ concentration depends on the latter. This is supported by a tight-binding model considering different values for the potentials on the nitrogen site and on its first neighbors.

Published
2015

26. Giant tunnel-electron injection in nitrogen-doped graphene

Author

Mattias Lau Nøhr Palsgaard, Yann Tison, Mads Brandbyge, Jérôme Lagoute, Sylvie Rousset, Amandine Bellec, Yann Girard, Vincent Repain, François Ducastelle, Edward H. Conrad, Nick Papior Andersen, Cyril Chacon, Frédéric Joucken, Robert Sporken, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre de Recherche en Physique de la Matière et du Rayonnement [Namur] (PMR), Université de Namur [Namur], Georgia Institute of Technology [Atlanta], Laboratoire d'étude des microstructures [Châtillon] (LEM - ONERA - CNRS), ONERA-Centre National de la Recherche Scientifique (CNRS), Center for Nanostructured Graphene, Université de Namur [Namur] (UNamur), and Centre National de la Recherche Scientifique (CNRS)-ONERA

Subjects
GRAPHENE, Materials science, 02 engineering and technology, Electron, PHYSICS, 01 natural sciences, Molecular physics, law.invention, [SPI.MAT]Engineering Sciences [physics]/Materials, symbols.namesake, Condensed Matter::Materials Science, AZOTE, law, Ab initio quantum chemistry methods, Condensed Matter::Superconductivity, 0103 physical sciences, Physics::Atomic and Molecular Clusters, Physics::Chemical Physics, 010306 general physics, Spectroscopy, Quantum tunnelling, Graphene, Fermi level, Conductance, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, symbols, ELECTRON, Scanning tunneling microscope, 0210 nano-technology
Abstract

International audience; Scanning tunneling microscopy experiments have been performed to measure the local electron injection in nitrogen-doped graphene on SiC(000¯1) and were successfully compared to ab initio calculations. In graphene, a gaplike feature is measured around the Fermi level due to a phonon-mediated tunneling channel. At nitrogen sites, this feature vanishes due to an increase of the elastic channel that is allowed because of symmetry breaking induced by the nitrogen atoms. A large conductance enhancement by a factor of up to 500 was measured at the Fermi level by comparing local spectroscopy at nitrogen sites and at carbon sites. Nitrogen doping can therefore be proposed as a way to improve tunnel-electron injection in graphene.

Published
2015

27. Electronic interaction between nitrogen atoms in doped graphene

Author

Luc Henrard, Dimpy Sharma, Yann Tison, Ahmed Ghedjatti, Cyril Chacon, Frédéric Joucken, Hakim Amara, Sylvie Rousset, Yann Girard, Vincent Repain, Jérôme Lagoute, François Ducastelle, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Groupe de Physique des Solides (GPS), Laboratoire Francis PERRIN (LFP - URA 2453), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), ONERA - The French Aerospace Lab [Châtillon], ONERA-Université Paris Saclay (COmUE), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), and ONERA

Subjects
Atoms, Electronic structure, Materials science, Nitrogen, Binding sites, Nitrogen-doping, Potential applications of graphene, STM, General Physics and Astronomy, Nanotechnology, 02 engineering and technology, Binding energy, 010402 general chemistry, 01 natural sciences, DFT, STS, law.invention, Tight binding, law, tight-binding, Physics::Atomic and Molecular Clusters, [CHIM]Chemical Sciences, General Materials Science, Point defects, Doping (additives), Scanning tunneling microscopy, Dopant, Graphene, General Engineering, nitrogen doping, Chemical bonds, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Chemical physics, Electronic properties, Density functional theory, Scanning tunneling microscope, 0210 nano-technology, Graphene nanoribbons
Abstract

cited By 20; International audience; Many potential applications of graphene require either the possibility of tuning its electronic structure or the addition of reactive sites on its chemically inert basal plane. Among the various strategies proposed to reach these objectives, nitrogen doping, i.e., the incorporation of nitrogen atoms in the carbon lattice, leads in most cases to a globally n-doped material and to the presence of various types of point defects. In this context, the interactions between chemical dopants in graphene have important consequences on the electronic properties of the systems and cannot be neglected when interpreting spectroscopic data or setting up devices. In this report, the structural and electronic properties of complex doping sites in nitrogen-doped graphene have been investigated by means of scanning tunneling microscopy and spectroscopy, supported by density functional theory and tight-binding calculations. In particular, based on combined experimental and simulation works, we have systematically studied the electronic fingerprints of complex doping configurations made of pairs of substitutional nitrogen atoms. Localized bonding states are observed between the Dirac point and the Fermi level in contrast with the unoccupied state associated with single substitutional N atoms. For pyridinic nitrogen sites (i.e., the combination of N atoms with vacancies), a resonant state is observed close to the Dirac energy. This insight into the modifications of electronic structure induced by nitrogen doping in graphene provides us with a fair understanding of complex doping configurations in graphene, as it appears in real samples. © 2015 American Chemical Society.

Published
2015

28. Building uniform and long-range ordered nanostructures on a surface by nucleation on a point defect array

Author

Yann Girard, Stanislas Rohart, Antonio Tejeda, V. Repain, Sylvie Rousset, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), and Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS]Physics [physics], Materials science, Nanostructure, business.industry, Nucleation, chemistry.chemical_element, 02 engineering and technology, Rate equation, Atmospheric temperature range, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Condensed Matter::Materials Science, Optics, chemistry, Chemical physics, 0103 physical sciences, General Materials Science, Kinetic Monte Carlo, 010306 general physics, 0210 nano-technology, business, Cobalt, Vicinal, Quantum tunnelling
Abstract

International Workshop on Self-Organized Nanostructures, Cargese, FRANCE, JUL 17-23, 2005; International audience; We present both experimental and simulated results of ordered growth of cobalt nano-islands on a Au(111) vicinal template. Firstly, the temperature range for ordered growth and the islands size distributions are investigated by a rate equation model and kinetic Monte Carlo (KMC) simulations. Secondly, the incidence of the surface structure on the growth of cobalt is studied in detail by means of variable temperature scanning tunnelling microscopy experiments and KMC simulations. The underlying atomic processes responsible for the ordered growth are discussed.

Published
2006

29. Grain boundaries in graphene on SiC(0001¯) substrate

Author

Frédéric Joucken, Jérôme Lagoute, Oleg V. Yazyev, Yann Tison, Vincent Repain, Fernando Gargiulo, Yann Girard, Cyril Chacon, Sylvie Rousset, Robert Sporken, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Groupe de Physique des Solides (GPS), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre d'Analyse et de Mathématique sociales (CAMS), École des hautes études en sciences sociales (EHESS)-Centre National de la Recherche Scientifique (CNRS), EPFL- Institute of Theoretical Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Aménités et dynamiques des espaces ruraux (UR ADBX), and Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)

Subjects
Models, Molecular, 02 engineering and technology, Substrate (electronics), Silicon carbide, Periodic grain boundaries, 01 natural sciences, law.invention, Microscopy, Scanning Tunneling, law, Models, Scanning tunneling microscopy and spectroscopy, General Materials Science, Physics, Microscopy, Condensed matter physics, Misorientation angle, 021001 nanoscience & nanotechnology, Condensed Matter Physics, scanning tunneling microscopy, Grain boundary, Charge carrier, Graphite, Scanning tunneling microscope, 0210 nano-technology, Small-angle grain boundaries, Silicon, Misorientation, surface property, Bar (music), Surface Properties, Periodic structures, FOS: Physical sciences, Bioengineering, chemistry, Scanning Tunneling, Out of plane buckling, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), 0103 physical sciences, [CHIM]Chemical Sciences, 010306 general physics, Spectroscopy, Ordered grain boundaries, Condensed Matter - Mesoscale and Nanoscale Physics, Graphene, Mechanical Engineering, Molecular, Buckling transitions, General Chemistry, Scanning tunneling spectroscopy, Grain boundaries, Density functional theory, chemical structure
Abstract

cited By 18; International audience; Grain boundaries in epitaxial graphene on the SiC(0001¯) substrate are studied using scanning tunneling microscopy and spectroscopy. All investigated small-angle grain boundaries show pronounced out-of-plane buckling induced by the strain fields of constituent dislocations. The ensemble of observations determines the critical misorientation angle of buckling transition θc = 19 ± 2°. Periodic structures are found among the flat large-angle grain boundaries. In particular, the observed θ = 33 ± 2° highly ordered grain boundary is assigned to the previously proposed lowest formation energy structural motif composed of a continuous chain of edge-sharing alternating pentagons and heptagons. This periodic grain boundary defect is predicted to exhibit strong valley filtering of charge carriers thus promising the practical realization of all-electric valleytronic devices. © 2014 American Chemical Society.

Published
2014

30. Long-range ordered nanodomains of grafted electroactive molecules

Author

Z. Qin, Yann Girard, Samia Zrig, Nicolas Battaglini, M. Marsault, P. Lang, Vincent Repain, S. Rousset, Romain Breitwieser, Jérôme Lagoute, C. Chacon, National Taiwan University [Taiwan] (NTU), Centre Interdisciplinaire de Nanoscience de Marseille (CINaM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Département Mécanismes d'Accidents (INRETS/MA), Institut National de Recherche sur les Transports et leur Sécurité (INRETS), Laboratoire catalyse et spectrochimie (LCS), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Interfaces, Traitements, Organisation et Dynamique des Systèmes (ITODYS (UMR_7086)), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), University of St Andrews, Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université Paris Diderot - Paris 7 (UPD7)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), University of St Andrews [Scotland], Knoop, Martina, Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Université de Caen Normandie (UNICAEN), and Normandie Université (NU)

Subjects
Models, Molecular, Nanostructure, Materials science, Surface Properties, Scanning tunneling spectroscopy, General Physics and Astronomy, Nanotechnology, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, [PHYS] Physics [physics], chemistry.chemical_compound, Terthiophene, Molecular conductance, Monolayer, Sulfhydryl Compounds, Physical and Theoretical Chemistry, Nanoscopic scale, [PHYS]Physics [physics], Electric Conductivity, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Nanostructures, Nanolithography, chemistry, Metals, Self-assembly, 0210 nano-technology
Abstract

We demonstrate the capability to build zero and one-dimensional electroactive molecular nanostructures ordered over a macroscopic scale and stable under ambient conditions. To realize these arrays, we use the selective grafting of functionalized thiols (juglon and terthiophene based) on a self-organized metallic template. The nanoscale patterning of the molecular conductance is demonstrated and analyzed by scanning tunneling spectroscopy. Finally, the influence of the nanostructuring on electro-chemical properties is measured, paving the way to an all-bottom-up fabrication of nanostructured templates for nanosciences. (C) 2013 AIP Publishing LLC.

Published
2013

31. Identification of nitrogen dopants in single-walled carbon nanotubes by scanning tunneling microscopy

Author

Toma Susi, Bing Zheng, Luc Henrard, Esko I. Kauppinen, Hong Lin, Jérôme Lagoute, Yann Tison, V. Repain, Yann Girard, S. Rousset, Annick Loiseau, François Ducastelle, Cyril Chacon, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry and Institute for Nanoscale Physics and chemistry (INPAC), Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), Groupe de Physique des Solides (GPS), Aménités et dynamiques des espaces ruraux (UR ADBX), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Laboratoire d'étude des microstructures [Châtillon] (LEM - ONERA - CNRS), ONERA-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)

Subjects
inorganic chemicals, Atoms, Electronic structure, Materials science, Van Hove singularities, Nitrogen, Van Hove singularity, Scanning tunneling spectroscopy, Nitrogen-doping, Selective chemistry of single-walled nanotubes, Analytical chemistry, Carbon nanotubes, General Physics and Astronomy, Mechanical properties of carbon nanotubes, 02 engineering and technology, Carbon nanotube, 01 natural sciences, law.invention, Condensed Matter::Materials Science, Single-walled carbon nanotubes (SWCN), law, 0103 physical sciences, Scanning tunneling microscopy and spectroscopy, Chemical vapor deposition, [CHIM]Chemical Sciences, General Materials Science, Point defects, 010306 general physics, Spectroscopy, Scanning tunneling microscopy, General Engineering, 021001 nanoscience & nanotechnology, Carbon, Optical properties of carbon nanotubes, Scanning tunnelling microscopy and spectroscopy, Chemical physics, Substitutional nitrogen, Density functional theory, Semi-conducting nanotubes, Scanning tunneling microscope, 0210 nano-technology, Atomic configuration, Spectroscopic measurements
Abstract

cited By 8; International audience; Using scanning tunnelling microscopy and spectroscopy, we investigated the atomic and electronic structure of nitrogen-doped single walled carbon nanotubes synthesized by chemical vapor deposition. The insertion of nitrogen in the carbon lattice induces several types of point defects involving different atomic configurations. Spectroscopic measurements on semiconducting nanotubes reveal that these local structures can induce either extended shallow levels or more localized deep levels. In a metallic tube, a single doping site associated with a donor state was observed in the gap at an energy close to that of the first van Hove singularity. Density functional theory calculations reveal that this feature corresponds to a substitutional nitrogen atom in the carbon network. © 2013 American Chemical Society.

Published
2013

32. Thermodynamics versus kinetics in a morphology transition of nanoparticles

Author

N. Moreau, Hervé Bulou, Christine Goyhenex, Virginie Speisser, Philippe Ohresser, Jérôme Lagoute, Fabrice Scheurer, Michelangelo Romeo, S. Rousset, Yann Girard, C. Chacon, B. Carrière, V. Repain, Edwige Otero, Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Département Mécanismes d'Accidents (INRETS/MA), Institut National de Recherche sur les Transports et leur Sécurité (INRETS), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Knoop, Martina, École normale supérieure - Paris (ENS Paris), École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP)

Subjects
[PHYS]Physics [physics], Materials science, Thermodynamic equilibrium, Bilayer, chemistry.chemical_element, Thermodynamics, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Electronic, Optical and Magnetic Materials, [PHYS] Physics [physics], Condensed Matter::Materials Science, chemistry, Picosecond, 0103 physical sciences, Atom, Monolayer, Physics::Atomic and Molecular Clusters, Stress relaxation, Cluster (physics), 010306 general physics, 0210 nano-technology, Palladium
Abstract

The morphology of cobalt, palladium, and platinum nanoclusters grown on a gold surface is analyzed from both thermodynamic and kinetic viewpoints. Although the thermodynamic equilibrium shape as a function of cluster size is similar for all three elements and shows a morphology transition from monolayer to bilayer, only Co clusters meet their stable state and undergo a transition. Atomistic simulations on a picosecond to nanosecond time scale evidence kinetic limitations for Pt and Pd, and allow us to understand the experimentally observed morphology for the different species. It is shown that stress relaxation, by strongly influencing the energy activation for atom hopping from first to second cluster layer and the magnitude of vibration of the atoms, is the determinant parameter for the existence or absence of the cluster morphology transition. DOI: 10.1103/PhysRevB.87.155404

Published
2013

33. Large magnetoresistance through a single molecule due to a spin-split hybridized orbital

Author

S. Rousset, Yann Girard, Jérôme Lagoute, S. L. Kawahara, Cyrille Barreteau, V. Repain, Alexander Smogunov, Cyril Chacon, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Groupe Modélisation et Théorie (GMT), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and Knoop, Martina

Subjects
Models, Molecular, Magnetoresistance, Scanning tunneling spectroscopy, Spin-polarized STM, Bioengineering, 02 engineering and technology, molecular orbital, 7. Clean energy, 01 natural sciences, [PHYS] Physics [physics], 0103 physical sciences, Electric Impedance, General Materials Science, Molecular orbital, Computer Simulation, 010306 general physics, density functional theory, [PHYS]Physics [physics], Condensed matter physics, Spin polarization, Spintronics, Chemistry, fullerene, Mechanical Engineering, Spin engineering, Spin polarized scanning tunneling microscopy, General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Magnetic Fields, Models, Chemical, Non-bonding orbital, Condensed Matter::Strongly Correlated Electrons, Fullerenes, 0210 nano-technology
Abstract

International audience; Using organic materials in spintronic devices raises a lot of expectation for future applications due to their flexibility, low cost, long spin lifetime, and easy functionalization. However, the interfacial hybridization and spin polarization between the organic layer and the ferromagnetic electrodes still has to be understood at the molecular scale. Coupling state-of-the-art spin-polarized scanning tunneling spectroscopy and spin-resolved ab initio calculations, we give the first experimental evidence of the spin splitting of a molecular orbital on a single non magnetic C-60 molecule in contact with a magnetic material, namely, the Cr(001) surface. This hybridized molecular state is responsible for an inversion of sign of the tunneling magnetoresistance depending on energy. This result opens the way to spin filtering through molecular orbitals.

Published
2012

34. Localized state and charge transfer in nitrogen-doped graphene

Author

V. Repain, Jérôme Lagoute, Luc Henrard, Cyril Chacon, Yann Girard, Robert Sporken, S. Rousset, Frédéric Joucken, Andrés R. Botello-Méndez, Damien Cabosart, J. Dumont, Bing Zheng, Jean-Christophe Charlier, Yann Tison, UCL - SST/IMCN/NAPS - Nanoscopic Physics, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie des Sufaces et Interfaces (ICSI), Centre National de la Recherche Scientifique (CNRS), Groupe de Physique des Solides (GPS), Aménités et dynamiques des espaces ruraux (UR ADBX), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Unité de Physico-Chimie et de Physique des Matériaux (PCPM), Université Catholique de Louvain = Catholic University of Louvain (UCL)-European Theoretical Spectroscopy Facility (ETSF), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), and Université Catholique de Louvain (UCL)-European Theoretical Spectroscopy Facility (ETSF)

Subjects
inorganic chemicals, Materials science, Scanning tunneling spectroscopy, FOS: Physical sciences, chemistry.chemical_element, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Spectral line, law.invention, Condensed Matter::Materials Science, law, Condensed Matter::Superconductivity, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Physics::Atomic and Molecular Clusters, [CHIM]Chemical Sciences, Physics::Chemical Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Doping, Charge density, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Nitrogen, 0104 chemical sciences, Electronic, Optical and Magnetic Materials, chemistry, Chemical physics, Density functional theory, Atomic physics, Scanning tunneling microscope, 0210 nano-technology, Carbon
Abstract

Nitrogen-doped epitaxial graphene grown on SiC(000?1) was prepared by exposing the surface to an atomic nitrogen flux. Using Scanning Tunneling Microscopy (STM) and Spectroscopy (STS), supported by Density Functional Theory (DFT) calculations, the simple substitution of carbon by nitrogen atoms has been identified as the most common doping configuration. High-resolution images reveal a reduction of local charge density on top of the nitrogen atoms, indicating a charge transfer to the neighboring carbon atoms. For the first time, local STS spectra clearly evidenced the energy levels associated with the chemical doping by nitrogen, localized in the conduction band. Various other nitrogen-related defects have been observed. The bias dependence of their topographic signatures demonstrates the presence of structural configurations more complex than substitution as well as hole-doping., 5 pages, accepted in PRB

Published
2012

35. Electronic capture and excitation of highly charged channeled ions

Author

D. Schmaus, A. Fleury, J. Dural, M. Chevallier, J. Remillieux, Yann Girard, Marcel Toulemonde, Dominique Vernhet, J. C. Poizat, M.S. Pravikoff, Denis Dauvergne, R. Kirsch, R. Del Moral, S. Andriamonje, A. L'Hoir, C. Röhl, J.P. Dufour, L. Faux, Y. Quere, Hermann Rothard, B. Blank, C. Cohen, Nelson Cue, J-P Rozet, Flores, Sylvie, Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), CAS-PHABIO, Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)

Subjects
Nuclear and High Energy Physics, Chemistry, Projectile, Electron capture, 01 natural sciences, 010305 fluids & plasmas, Ion, [PHYS.PHYS.PHYS-INS-DET] Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], 0103 physical sciences, Radiative transfer, Heavy ion, Experimental work, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Atomic physics, Nuclear Experiment, 010306 general physics, Fermi gas, Instrumentation, Excitation
Abstract

Two aspects of heavy ion channeling are presented. The first aspect is related to the fact that channeled ions interact only with the most loosely bound target electrons. One can take benefit of this feature to study processes such as radiative electron capture (REC) and resonant transfer and excitation (RTE) in a dense quasi-free electron gas. The experimental work, performed at GANIL, devoted to these two processes is described. A possible extension to Nuclear RTE or NEEC (nuclear excitation by electron capture) studies is also described. The second aspect discussed is related to the periodicity of the potential experienced by channeled ions. We show that in a well chosen case this could lead to a significant and detectable coherent excitation of the projectile nucleus.

Published
1994

36. Spin-polarized scanning tunneling microscopy and spectroscopy study of chromium on a Cr(001) surface

Author

V. Repain, C. Chacon, S. L. Kawahara, Yann Girard, Jérôme Lagoute, S. Rousset, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Département Mécanismes d'Accidents (INRETS/MA), Institut National de Recherche sur les Transports et leur Sécurité (INRETS), and Knoop, Martina

Subjects
[PHYS]Physics [physics], Auger electron spectroscopy, Chemistry, Scanning tunneling spectroscopy, Analytical chemistry, chemistry.chemical_element, Spin polarized scanning tunneling microscopy, 02 engineering and technology, Substrate (electronics), 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Electron beam physical vapor deposition, law.invention, [PHYS] Physics [physics], Chromium, law, 0103 physical sciences, General Materials Science, Scanning tunneling microscope, 010306 general physics, 0210 nano-technology, Spectroscopy
Abstract

Several tens of chromium layers were deposited at 250 degrees C on a Cr(001) surface and investigated by spin-polarized scanning tunneling microscopy (SP-STM), Auger electron spectroscopy (AES) and scanning tunneling spectroscopy (STS). Chromium is found to grow with a mound-like morphology resulting from the stacking of several monolayers which do not uniformly cover the whole surface of the substrate. The terminal plane consists of an irregular array of Cr islands with lateral sizes smaller than 20 x 20 nm(2). Combined AES and STS measurements reveal the presence of a significant amount of segregants prior to and after deposition. A detailed investigation of the surface shows that it consists of two types of patches. Thanks to STS measurements, the two types of area have been identified as being either chromium pure or segregant rich. SP-STM experiments have evidenced that the antiferromagnetic layer coupling remains in the chromium mounds after deposition and is not significantly affected by the presence of the segregants.

Published
2011

37. Interplay between interfacial and structural properties on the magnetism of self-organized core-shell Co/Pt supported nanodots

Author

N. Moreau, F. Scheurer, S. Rousset, Christine Goyhenex, Paolo Campiglio, Hervé Bulou, Philippe Ohresser, Jérôme Lagoute, V. Repain, J. Klein, Hélène Magnan, Emiliano Fonda, C. Chacon, Yann Girard, Knoop, Martina, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Département Mécanismes d'Accidents (INRETS/MA), Institut National de Recherche sur les Transports et leur Sécurité (INRETS), University of Minnesota [Twin Cities] (UMN), University of Minnesota System, Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS-PSL), École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), and University of Minnesota [Twin Cities]

Subjects
[PHYS]Physics [physics], Materials science, Kerr effect, Condensed matter physics, Magnetic moment, Magnetic circular dichroism, Magnetism, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Electronic, Optical and Magnetic Materials, law.invention, [PHYS] Physics [physics], Hysteresis, Magnetic anisotropy, law, 0103 physical sciences, Nanodot, Scanning tunneling microscope, 010306 general physics, 0210 nano-technology
Abstract

International audience; We have studied the influence of Pt capping on the magnetic properties of self-organized Co nanodots by means of complementary structural and magnetic investigation techniques. The growth of monodisperse 5 nm diameter Co dots on a Au(111) surface and its progressive coverage by Pt were performed under ultrahigh vacuum conditions and imaged by scanning tunneling microscopy, revealing a weak mixing at room temperature. The Co/Pt core-shell structure was studied both by molecular-dynamics simulations and surface extended x-ray-absorption fine structure, showing a global dilatation of the Co core. Both magnetic moments and hysteresis cycles at various temperatures were measured using x-ray magnetic circular dichroism, revealing a slight increase of the magnetic moments and the out-of-plane magnetic anisotropy after Pt capping. Moreover, the variation of magnetic anisotropy as a function of capping was followed in situ by the magneto-optical Kerr effect. Our investigations demonstrate that interfacial hybridization between Co and Pt is dominant over magnetoelastic contribution in this system.

Published
2011

38. Electronic properties of Fe clusters on a Au(111) surface

Author

V. Repain, Madhura Marathe, Cyril Chacon, Jérôme Lagoute, S. Rousset, Shobhana Narasimhan, Alexandre Delga, Yann Girard, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Theoretical Sciences Unit, and Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR)

Subjects
[PHYS]Physics [physics], Local density of states, Materials science, Nanostructure, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Molecular physics, Electronic, Optical and Magnetic Materials, law.invention, Condensed Matter::Materials Science, Effective mass (solid-state physics), Ab initio quantum chemistry methods, law, 0103 physical sciences, Scanning tunneling microscope, 010306 general physics, 0210 nano-technology, Spectroscopy, Electronic properties, Surface states
Abstract

The electronic states of self-organized Fe nanoislands on a Au(111) surface have been investigated using low-temperature scanning tunneling microscopy and spectroscopy. We show that the local density of states is dominated by Shockley surface states confined in the nanostructures. Comparing the experimental dispersion diagram with a free-electron model we derive the effective mass ${m}^{*}=0.39\phantom{\rule{0.16em}{0ex}}{m}_{e}$ and the band onset ${E}_{0}=\ensuremath{-}420$ meV of these states. Ab initio calculations show the existence of the Shockley surface states in the Fe layer, in agreement with the experiment, and reveal that they are fully spin polarized.

Published
2011

39. Prediction of reconstruction in heteroepitaxial systems using the Frenkel-Kontorova model

Author

Yann Girard, Jérôme Lagoute, S. Mehendale, S. Rousset, Cyril Chacon, Madhura Marathe, V. Repain, Shobhana Narasimhan, Département Mécanismes d'Accidents (INRETS/MA), Institut National de Recherche sur les Transports et leur Sécurité (INRETS), Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), and Knoop, Martina

Subjects
Surface (mathematics), Physics, [PHYS]Physics [physics], Nanostructure, Condensed matter physics, Ab initio, Stacking, Nanotechnology, 02 engineering and technology, Substrate (electronics), 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, [PHYS] Physics [physics], Electronic, Optical and Magnetic Materials, Molecular dynamics, Simple (abstract algebra), 0103 physical sciences, Density functional theory, 010306 general physics, 0210 nano-technology
Abstract

Many heteroepitaxial metal-on-metal systems reconstruct into patterns of alternating domains of stacking faults separated by partial misfit dislocations. Here, we use two approaches to investigate the question of whether these can be predicted and controlled: (i) We map the system onto a one-dimensional Frenkel-Kontorova model, and then obtain a simple criterion to determine whether or not the surface will reconstruct; this had earlier been done for homoepitaxial systems, but is here generalized to the heteroepitaxial case. (ii) The two-dimensional Frenkel-Kontorova model is solved numerically by performing quenched molecular dynamics simulations. The necessary microscopic parameters are obtained by performing ab initio density functional theory calculations on the unreconstructed systems. The systems considered are overlayers of Fe, Co, Pt, Ag, Au, and Pb on a Ru(0001) substrate, as well as clean Ru(0001). The predictions of the two approaches agree with one another as well as with experiment. Both the presence and periodicity of the reconstruction are very sensitive to the value of ``chemical potential'' $\ensuremath{\Gamma}$. Accordingly, we suggest that $\ensuremath{\Gamma}$ can be used to tune the periodicity so as to obtain a desired nanotemplate for subsequent growth of self-organized nanostructures.

Published
2011

40. Imaging the symmetry breaking of molecular orbitals in single-wall carbon nanotubes

Author

Patrick Hermet, Jérôme Lagoute, A. Loiseau, V. Repain, Cyril Chacon, Hong Lin, Luc Henrard, S. Rousset, Yann Girard, François Ducastelle, Hakim Amara, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), LEM, UMR 104 CNRS-ONERA, Université Paris Saclay [Châtillon], ONERA-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'étude des microstructures [Châtillon] (LEM - ONERA - CNRS), ONERA-Centre National de la Recherche Scientifique (CNRS), Research Centre in Physics of Matter and Radiation (PMR), LISE Laboratory, Université de Namur [Namur], LEM, UMR 104 CNRS-ONERA, Université Paris Saclay (COmUE) [Châtillon], ONERA-Centre National de la Recherche Scientifique (CNRS)-Université Paris Saclay (COmUE), and Université de Namur [Namur] (UNamur)

Subjects
[PHYS]Physics [physics], Materials science, Condensed matter physics, Selective chemistry of single-walled nanotubes, Molecular orbital diagram, Molecular orbital theory, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Electronic, Optical and Magnetic Materials, Optical properties of carbon nanotubes, Chemical physics, Linear combination of atomic orbitals, 0103 physical sciences, Valence bond theory, Molecular orbital, 010306 general physics, 0210 nano-technology, Natural bond orbital
Abstract

International audience; Carbon nanotubes have attracted considerable interest for their unique electronic properties. They are fascinating candidates for fundamental studies of one dimensional materials as well as for future molecular electronics applications. The molecular orbitals of nanotubes are of particular importance as they govern the transport properties and the chemical reactivity of the system. Here, we show for the first time a complete experimental investigation of molecular orbitals of single wall carbon nanotubes using atomically resolved scanning tunneling spectroscopy. Local conductance measurements show spectacular carbon-carbon bond asymmetry at the Van Hove singularities for both semiconducting and metallic tubes, demonstrating the symmetry breaking of molecular orbitals in nanotubes. Whatever the tube, only two types of complementary orbitals are alternatively observed. An analytical tight-binding model describing the interference patterns of pi orbitals confirmed by ab initio calculations, perfectly reproduces the experimental results.

Published
2010

41. Spin-Wave-Assisted Thermal Reversal of Epitaxial Perpendicular Magnetic Nanodots

Author

S. Rousset, Paolo Campiglio, André Thiaville, Jérôme Lagoute, Yann Girard, Stanislas Rohart, Cyril Chacon, Y. Nahas, V. Repain, Laboratoire de Physique des Solides (LPS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et d'Etude des Matériaux (UMR 8213) (LPEM), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Département Mécanismes d'Accidents (INRETS/MA), Institut National de Recherche sur les Transports et leur Sécurité (INRETS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et d'Etude des Matériaux (LPEM), Centre National de la Recherche Scientifique (CNRS)-ESPCI ParisTech-Université Pierre et Marie Curie - Paris 6 (UPMC), and Knoop, Martina

Subjects
[PHYS]Physics [physics], Materials science, Condensed matter physics, General Physics and Astronomy, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Atomic units, Power law, Magnetic susceptibility, [PHYS] Physics [physics], symbols.namesake, Magnetic anisotropy, Spin wave, 0103 physical sciences, symbols, Nanodot, 010306 general physics, 0210 nano-technology, Hamiltonian (quantum mechanics), Excitation
Abstract

The magnetic susceptibility of self-organized two-dimensional Co nanodots on Au(111) has been measured as a function of their size in the 2-7 nm diameter range. We show that the activation energy for the thermal reversal displays a power law behavior with the dot volume. Atomic scale simulations based on the Heisenberg Hamiltonian show that this behavior is due to a deviation from the macrospin model for dot size as small as 3 nm in diameter. This discrepancy is attributed to finite temperature effects through the thermal excitation of spin-wave modes inside the particles.

Published
2010

42. Elastic displacements and step interactions on metallic surfaces: Grazing-incidence x-ray diffraction andab initiostudy of Au(332)

Author

Jaita Paul, Yves Garreau, Shobhana Narasimhan, Nisha Mammen, Sylvie Rousset, Geoffroy Prévot, Alessandro Coati, Yann Girard, and Vincent Repain

Subjects
Diffraction, Physics, business.industry, Relaxation (NMR), Ab initio, 02 engineering and technology, Interaction energy, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Molecular physics, Electronic, Optical and Magnetic Materials, Dipole, Optics, 0103 physical sciences, X-ray crystallography, 010306 general physics, 0210 nano-technology, business, Anisotropy, Vicinal
Abstract

We have studied the energetics, relaxation, and interactions of steps on the Au(332) vicinal surface using a combination of grazing incidence x-ray diffraction, anisotropic linear elasticity theory, and ab initio density-functional theory. We find that the initial force distribution on a bulk-truncated surface, as well as the resulting pattern of atomic relaxations, can be reproduced excellently by a buried dipole elastic model. The close agreement obtained between experimental and calculated x-ray diffraction profiles allows us to precisely determine the value of the elastic dipole density at the steps. We also use these results to obtain an experimental estimate of the surface stress on an unreconstructed Au(111) facet, ${\ensuremath{\tau}}_{\text{Au}(111)}=2.3\ifmmode\pm\else\textpm\fi{}0.4\text{ }{\text{Nm}}^{\ensuremath{-}1}$, and the value of the step-step elastic interaction energy $A=950\ifmmode\pm\else\textpm\fi{}150\text{ }\text{meV}\text{ }\text{\AA{}}$.

Published
2010

43. Ordered Surface Alloy of Bulk-Immiscible Components Stabilized by Magnetism

Author

Madhura Marathe, Yann Girard, S. Rousset, C. Chacon, Shobhana Narasimhan, Jérôme Lagoute, S. Mehendale, V. Repain, Département Mécanismes d'Accidents (INRETS/MA), Institut National de Recherche sur les Transports et leur Sécurité (INRETS), Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), and Knoop, Martina

Subjects
[PHYS]Physics [physics], Materials science, Magnetic moment, Magnetism, Surface stress, Alloy, General Physics and Astronomy, 02 engineering and technology, Substrate (electronics), engineering.material, 021001 nanoscience & nanotechnology, 01 natural sciences, [PHYS] Physics [physics], law.invention, Nuclear magnetic resonance, Ab initio quantum chemistry methods, Chemical physics, law, 0103 physical sciences, Atom, engineering, Scanning tunneling microscope, 010306 general physics, 0210 nano-technology
Abstract

Using scanning tunneling microscopy and a diffraction experiment, we have discovered a new ordered surface alloy made out of two bulk-immiscible components, Fe and Au, deposited on a Ru(0001) substrate. In such a system, substrate-mediated strain interactions are believed to provide the main driving force for mixing. However, spin-polarized ab initio calculations show that the most stable structures are always the ones with the highest magnetic moment per Fe atom and not the ones minimizing the surface stress, in remarkable agreement with the observations. This opens up novel possibilities for creating materials with unique properties of relevance to device applications.

Published
2010

44. Interplay between ordered growth and intermixing of Pt on patterned Au surfaces

Author

S. Rousset, Yann Girard, V. Repain, Cyril Chacon, Y. Nahas, Laboratoire de Physique et d'Etude des Matériaux (LPEM), Centre National de la Recherche Scientifique (CNRS)-ESPCI ParisTech-Université Pierre et Marie Curie - Paris 6 (UPMC), Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Département Mécanismes d'Accidents (INRETS/MA), Institut National de Recherche sur les Transports et leur Sécurité (INRETS), Laboratoire de Physique et d'Etude des Matériaux (UMR 8213) (LPEM), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
STM, chemistry.chemical_element, 02 engineering and technology, 01 natural sciences, law.invention, Surface pattern, law, 0103 physical sciences, Materials Chemistry, Surface layer, 010306 general physics, Platinum, [PHYS]Physics [physics], Surfaces and Interfaces, Atmospheric temperature range, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Surfaces, Coatings and Films, Crystallography, Pt deposition, chemistry, Nanodot, Gold, Scanning tunneling microscope, 0210 nano-technology
Abstract

We have investigated the growth of submonolayer coverage of platinum on two gold surfaces (Au(1 1 1) and Au(7 8 8)), at temperatures ranging from 110 K to 300 K. The Scanning Tunneling Microscope images reveal a competition between the ordered growth of nanodots and a random intermixing between Pt and Au. The Pt deposition on the Au(1 1 1) surface at room temperature shows an ordered growth limited by the insertion of Pt atoms into the surface layer and the subsequent modifications of the herringbone surface pattern. In contrast, for Pt on the Au(7 8 8) stepped surface, perfect ordered growth is observed over a wide temperature range. (C) 2010 Elsevier By. All rights reserved.

Published
2010

45. Kondo peak splitting on a single adatom coupled to a magnetic cluster

Author

J. Klein, Yann Girard, S. L. Kawahara, V. Repain, Cyril Chacon, Jérôme Lagoute, S. Rousset, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Département Mécanismes d'Accidents (INRETS/MA), Institut National de Recherche sur les Transports et leur Sécurité (INRETS), University of Minnesota [Twin Cities] (UMN), University of Minnesota System, Knoop, Martina, and University of Minnesota [Twin Cities]

Subjects
[PHYS]Physics [physics], Materials science, Condensed matter physics, Kondo insulator, Fano resonance, Spin polarized scanning tunneling microscopy, Condensed Matter Physics, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 01 natural sciences, Resonance (particle physics), [PHYS] Physics [physics], 010305 fluids & plasmas, Electronic, Optical and Magnetic Materials, law.invention, Condensed Matter::Materials Science, Impurity, law, 0103 physical sciences, Atom, Physics::Atomic and Molecular Clusters, Condensed Matter::Strongly Correlated Electrons, Kondo effect, Scanning tunneling microscope, 010306 general physics
Abstract

The Kondo resonance induced by a single cobalt adatom interacting with a ferromagnetic iron nanocluster is measured using low-temperature scanning tunneling microscopy. The persistence of the Kondo resonance is evidenced along with the predicted splitting of the spectral density peak for a Kondo impurity surrounded by a spin-polarized electron bath. Reversible quenching of the split feature is observed using atom manipulation between adjacent adsorption sites. Using a Green's-function formalism, we model a double Fano resonance leading to a quantitative insight of our observations.

Published
2010

46. Discontinuous vs. continuous spin reorientation transition of magnetic films on vicinal surfaces

Author

G. Rodary, Jacques Ferré, Sylvie Rousset, J. H. Gao, Yann Girard, Jérôme Lagoute, M. Elsen, Cyril Chacon, Vincent Repain, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Département Mécanismes d'Accidents (INRETS/MA), Institut National de Recherche sur les Transports et leur Sécurité (INRETS), Laboratoire de Physique des Solides (LPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), and Knoop, Martina

Subjects
[PHYS]Physics [physics], Materials science, Kerr effect, Condensed matter physics, General Physics and Astronomy, 02 engineering and technology, Edge (geometry), 021001 nanoscience & nanotechnology, 01 natural sciences, [PHYS] Physics [physics], Condensed Matter::Materials Science, 0103 physical sciences, Surface roughness, Magnetic films, 010306 general physics, 0210 nano-technology, Anisotropy, Vicinal, Spin-½
Abstract

The Spin Reorientation Transition (SRT) of Co ultrathin films grown on two Au(111) vicinal surfaces with the same step density but different step edge microfacets has been investigated by in situ magneto-optical Kerr effect. A drastic change in the width of the SRT is reported and is explained by the difference, measured by STM, of the anisotropic surface roughness. A general model, taking into account only uniaxial first-order terms in the anisotropy, is able to explain quantitatively the transition from a continuous to a discontinuous SRT as function of the anisotropic surface roughness. This model is generally applicable to magnetic ultrathin films grown on vicinal surfaces. Copyright (C) EPLA, 2009

Published
2009

47. GeV xenon ions channeled through a silicon crystal

Author

M. Schosnig, C. Cohen, K. O. Groeneveld, D. Schmaus, J. Dural, J. Remillieux, S. Andriamonje, Yann Girard, J. C. Poizat, Michel Chevallier, R. Genre, Y. Quere, Marcel Toulemonde, R. Kirsch, J. Kemmler, A. L'Hoir, Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), CAS-PHABIO, Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), and Flores, Sylvie

Subjects
Nuclear and High Energy Physics, Radiation, Materials science, [PHYS.PHYS.PHYS-ATOM-PH]Physics [physics]/Physics [physics]/Atomic Physics [physics.atom-ph], chemistry.chemical_element, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, Ion, Monocrystalline silicon, Xenon, chemistry, 0103 physical sciences, General Materials Science, [PHYS.PHYS.PHYS-ATOM-PH] Physics [physics]/Physics [physics]/Atomic Physics [physics.atom-ph], Atomic physics, 010306 general physics
Abstract

CAS

Published
1991

48. Spin reorientation transition and magnetic domain structure of Co ultrathin films grown on a faceted Au(455) surface

Author

Vincent Repain, Guillemim Rodary, Jian Hua Gao, Sylvie Rousset, Yann Girard, Antonio Tejeda, Cyril Chacon, Rachid Belkhou, Nicolas Rougemaille, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Synchrotron ELETTRA, ELETTRA, MNM - Micro et NanoMagnétisme, Institut Néel (NEEL), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), Micro et NanoMagnétisme (MNM), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Magnetic domain, Magnetism, 75.30.Gw, 68.37.Xy, 75.70.Kw, 75.70.Ak, 02 engineering and technology, 01 natural sciences, Magnetization, Condensed Matter::Materials Science, PEEM, 0103 physical sciences, surface, faceted, 010306 general physics, domains, Condensed matter physics, Magnetic circular dichroism, XMCD, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Photoemission electron microscopy, Magnetic anisotropy, Domain wall (magnetism), X-ray magnetic circular dichroism, magnetism, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0210 nano-technology
Abstract

International audience; The spin reorientation transition (SRT) and magnetic domain structure of Co ultrathin films on faceted Au(455) surfaces have been investigated as a function of thickness by using magneto-optic Kerr effect and x-ray photoemission electron microscopy in combination with x-ray magnetic circular dichroism. The magnetization easy axis of the Co films is found to rotate from an out-of-plane to an in-plane orientation perpendicular to the atomic steps of the substrate due to the dominant contribution of the step-induced magnetic anisotropy. Moreover, magnetic stripe domains are observed to replicate the underlying periodic facets of the Au surface. Depending on the facet, the SRT occurs at a well-defined critical thickness and proceeds via a different mechanism: a state of uniform canted magnetization is formed for (233) facets, while the SRT involves continuous magnetization rotation followed by the nucleation of small in-plane magnetic domains for (677) facets.

Published
2008

49. Influence of grain boundaries on the magnetization reorientation transition in ultrathin films

Author

Robert Stamps, Yann Girard, Stanislas Rohart, Sylvie Rousset, Guillemin Rodary, Antonio Tejeda, and Vincent Repain

Subjects
Materials science, Condensed matter physics, Magnetization reversal, Spin polarized scanning tunneling microscopy, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Electronic, Optical and Magnetic Materials, law.invention, Condensed Matter::Materials Science, Magnetization, law, 0103 physical sciences, Grain boundary, Nanometre, Scanning tunneling microscope, 010306 general physics, 0210 nano-technology
Abstract

A magnetic reorientation transition is studied in situ in model experimental systems of Co grown on Au(111) and Au(788). Results from magneto-optic measurements and scanning tunneling microscopy, obtained on these two different self-ordered systems, demonstrate that grain boundaries formed during the film growth strongly influence the magnetic properties of the films. The nanometer scale of the magnetization reversal at the transition makes the temperature an essential parameter to predict experimental features observed in the magnetic reorientation transition.

Published
2007

50. Self-organized systems for measuring surface stress at the nanoscale: N and O adsorption on Cu(001)

Author

Yves Garreau, Bernard Croset, Yann Girard, Geoffroy Prévot, Alessandro Coati, Institut des Nanosciences de Paris (INSP), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nanostructure, Materials science, Surface stress, Linear elasticity, Analytical chemistry, chemistry.chemical_element, 02 engineering and technology, Crystal structure, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Copper, Electronic, Optical and Magnetic Materials, Adsorption, chemistry, 0103 physical sciences, X-ray crystallography, Elasticity (economics), [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, 0210 nano-technology
Abstract

International audience; We have studied, by grazing incidence x-ray diffraction, the surface stress variation under nitrogen and oxygen adsorption on Cu(001), exploiting the nitrogen self-organization on Cu(001). The measured structure factors are analyzed in the framework of linear elasticity theory. This allows us to calculate the elastic displacements in the bulk from the surface stress discontinuities located at the domain boundaries between the different phases that are present at the surface. We find that the variations of surface stress upon adsorption are of the order of 5.5 Nm(-1) for the N/Cu(001)-c(2x2) structure and 1.2 Nm(-1) for O/Cu(001)-c(2x2) structure. For both cases, elastic interactions due to surface stress variations are higher than electrostatic interactions. In addition, we have precisely determined the atomic structure of the c(2x2) N/Cu(001) and O/Cu(001) (2 root 2 x root 2)R45 degrees structures, showing that there is no significant Cu buckling in the c(2x2) N/Cu(001) case.

Published
2006

Catalog

Books, media, physical & digital resources
See catalog results