Author: "Cyril Chacon" / Language: english - Searchworks@Jio Institute Digital Library Search Results

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34 results on '"Cyril Chacon"'

1. Higher-indexed Moiré patterns and surface states of MoTe2/graphene heterostructure grown by molecular beam epitaxy

Author: Trung T. Pham, Péter Vancsó, Márton Szendrő, Krisztián Palotás, Roshan Castelino, Mehdi Bouatou, Cyril Chacon, Luc Henrard, Jérôme Lagoute, and Robert Sporken
Subjects: Materials of engineering and construction. Mechanics of materials, TA401-492, Chemistry, QD1-999
Abstract: Abstract Stabilization of the 2H phase of MoTe2 during molecular beam epitaxy (MBE) growth on graphene terminated 6H-SiC(0001) is highly desirable in order to take advantage of its promising properties in electronic applications. By properly adjusting the conditions, direct growth of the highly crystalline 2H phase of MoTe2 has been achieved. In such van der Waals heterostructure, the atomically-clean interface between graphene and MoTe2 permits the electronic coupling between the adjacent layers and the emergence of a high variety of Moiré patterns. In this paper, we investigate a single layer of 2H-MoTe2 grown on graphene by MBE and we present scanning tunneling microscopy (STM) investigations combined with density functional theory (DFT) calculations and simulations of STM images. Our results show that the STM images of the MoTe2/graphene heterostructure surprisingly amplify the otherwise weak Moiré potential modulations leading to the appearance of unique higher-indexed Moiré patterns. These patterns are unusually rich with many Fourier-overtones and show a remarkable variety of different applied bias voltages, revealing the complex electronic features of the heterostructure.
Published: 2022
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2. Quantum Transport in Large-Scale Patterned Nitrogen-Doped Graphene

Author: Aleksander Bach Lorentzen, Mehdi Bouatou, Cyril Chacon, Yannick J. Dappe, Jérôme Lagoute, and Mads Brandbyge
Subjects: graphene, nitrogen doping, patterning, quantum transport calculations, tight-binding model, Chemistry, QD1-999
Abstract: It has recently been demonstrated how the nitrogen dopant concentration in graphene can be controlled spatially on the nano-meter scale using a molecular mask. This technique may be used to create ballistic electron optics-like structures of high/low doping regions; for example, to focus electron beams, harnessing the quantum wave nature of the electronic propagation. Here, we employ large-scale Greens function transport calculations based on a tight-binding approach. We first benchmark different tight-binding models of nitrogen in graphene with parameters based on density functional theory (DFT) and the virtual crystal approximation (VCA). Then, we study theoretically how the random distribution within the masked regions and the discreteness of the nitrogen scattering centers impact the transport behavior of sharp n−p and n−n′ interfaces formed by different, realistic nitrogen concentrations. We investigate how constrictions for the current can be realized by patterned high/low doping regions with experimentally feasible nitrogen concentrations. The constrictions can guide the electronic current, while the quantized conductance is significantly washed out due to the nitrogen scattering. The implications for device design is that a p−n junction with nitrogen corrugation should still be viable for current focusing. Furthermore, a guiding channel with less nitrogen in the conducting canal preserves more features of quantized conductance and, therefore, its low-noise regime.
Published: 2023
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3. Molecular-scale dynamics of light-induced spin cross-over in a two-dimensional layer

Author: Kaushik Bairagi, Olga Iasco, Amandine Bellec, Alexey Kartsev, Dongzhe Li, Jérôme Lagoute, Cyril Chacon, Yann Girard, Sylvie Rousset, Frédéric Miserque, Yannick J Dappe, Alexander Smogunov, Cyrille Barreteau, Marie-Laure Boillot, Talal Mallah, and Vincent Repain
Subjects: Science
Abstract: 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
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4. Change of cobalt magnetic anisotropy and spin polarization with alkanethiolates self-assembled monolayers

Author: Paolo Campiglio, Romain Breitwieser, Vincent Repain, Solène Guitteny, Cyril Chacon, Amandine Bellec, Jérôme Lagoute, Yann Girard, Sylvie Rousset, Adele Sassella, Mighfar Imam, and Shobhana Narasimhan
Subjects: magnetic anisotropy, self-assembled monolayers, scanning tunneling microscopy, Science, Physics, QC1-999
Abstract: We demonstrate that the deposition of a self-assembled monolayer of alkanethiolates on a 1 nm thick cobalt ultrathin film grown on Au(111) induces a spin reorientation transition from in-plane to out-of-plane magnetization. Using ab initio calculations, we show that a methanethiolate layer changes slightly both the magnetocrystalline and shape anisotropy, both effects almost cancelling each other out for a 1 nm Co film. Finally, the change in hysteresis cycles upon alkanethiolate adsorption could be assigned to a molecular-induced roughening of the Co layer, as shown by STM. In addition, we calculate how a methanethiolate layer modifies the spin density of states of the Co layer and we show that the spin polarization at the Fermi level through the organic layer is reversed as compared to the uncovered Co. These results give new theoretical and experimental insights for the use of thiol-based self-assembled monolayers in spintronic devices.
Published: 2015
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5. Growth and local electronic properties of Cobalt nanodots underneath graphene on SiC(0001)

Author: Yann Girard, Sarah Benbouabdellah, Outhmane Chahib, Cyril Chacon, Amandine Bellec, Vincent Repain, Jérôme Lagoute, Yannick J. Dappe, César González, Wei-Bin Su, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université Paris-Saclay, CEA, CNRS, SPEC, 91191 Gif-sur-Yvette, France, Departamento de Fisica de Materiales, Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), and Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
Subjects: Scanning tunneling microscopy / spectroscopy, Density functional theory calculations, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], General Materials Science, General Chemistry, Cobalt, Silicon carbide, Graphene, Field effect resonance
Abstract: International audience; The coupling of graphene with a ferromagnetic material opens opportunities for technological innovations in spintronics. To obtain this coupling it is necessary to control the elaboration of interfaces at the atomic scale. Here, we present results on cobalt intercalation between graphene and a buffer layer supported on a SiC(0001) substrate. As a result, we obtain cobalt islands covered by graphene whose local electronic properties are measured by scanning tunneling microscopy and spectroscopy. These islands reveal two very distinct shapes and properties. Small-islands with atomic height and very narrow size distribution and, more interestingly, flat cobalt nanodots lower than one nanometer high, that are encapsulated by graphene. Compared to a graphene monolayer on SiC, those nanodots exhibit very different spectroscopic signatures. Using dI/dV local differential conductance spectra together with an analysis of image potential surface states measured thanks to dz/dV spectra, we show that graphene on the nanodots is neutrally charged. Moreover, its 4.65 eV work function is surprisingly larger than the predicted value of 3.8 eV for graphene on Co. First principle calculations show that those Co nanodots can be seen as cobalt bilayer sandwiched between two carbon planes.
Published: 2023
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6. Visualizing In-Plane Junctions in Nitrogen-Doped Graphene

Author: Mehdi Bouatou, Cyril Chacon, Aleksander Bach Lorentzen, Huu Thoai Ngo, Yann Girard, Vincent Repain, Amandine Bellec, Sylvie Rousset, Mads Brandbyge, Yannick J. Dappe, Jérôme Lagoute, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), 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), Groupe Modélisation et Théorie (GMT), 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-20-CE09-0023,DEFINE2D,Ingénierie des défauts dans les matériaux 2D: propriétés à l'échelle atomique et interaction avec des molécules(2020)
Subjects: Biomaterials, p-n junction, graphene, Electrochemistry, nitrogen doping, scanning tunneling microscopy, scanning tunneling spectroscopy, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Condensed Matter Physics, Electronic, Optical and Magnetic Materials
Abstract: International audience; Controlling the spatial distribution of dopants in graphene is the gateway to the realization of graphene-based electronic components. Here, we show that a submonolayer of self-assembled physisorbed molecules can be used as a resist during a post-synthesis nitrogen doping process to realize a nanopatterning of nitrogen dopants in graphene. The resulting formation of domains with different nitrogen concentrations allows obtaining nn' and pn junctions in graphene. We use scanning tunneling microscopy to measure the electronic properties of the junctions at the atomic scale and reveal their intrinsic width that is found to be around 7 nm corresponding to a sharp junction regime.
Published: 2022
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7. 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
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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
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9. 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
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10. 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
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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
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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
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13. 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
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14. 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

15. 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
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16. 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
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17. 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
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18. C$_{60}$ as an Atom Trap to Capture Co Adatoms

Author: Sylvie Rousset, Peng Yang, Dongzhe Li, Yannick J. Dappe, Cyril Chacon, Cyrille Barreteau, Alexander Smogunov, Yann Girard, Vincent Repain, Jérôme Lagoute, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Xidian University, 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), DTU Nanotech, Technical University of Denmark [Lyngby] (DTU), The calculations in this work was performed using HPC resources from GENCI-CINES (Grant Nos. x2013096813), 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 Danmarks Tekniske Universitet = Technical University of Denmark (DTU)
Subjects: [PHYS]Physics [physics], Chemistry, Scanning tunneling spectroscopy, Trapping, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, law.invention, Metal, Condensed Matter::Materials Science, General Energy, Chemical physics, law, visual_art, Atom, Physics::Atomic and Molecular Clusters, visual_art.visual_art_medium, Cluster (physics), Molecule, Density functional theory, Physical and Theoretical Chemistry, Atomic physics, Scanning tunneling microscope, Physics::Chemical Physics, [MATH]Mathematics [math]
Abstract: International audience; C$_{60}$ molecules were used to trap Co adatoms and clusters on a Au(111) surface using atomic/molecular manipulation with a scanning tunneling microscope. Two manipulation pathways (successive integration of single Co atoms in one molecule or direct integration of a Co cluster) were found to efficiently allow the formation of complexes mixing a C$_{60}$ molecule with Co atoms. Scanning tunneling spectroscopy reveals the robustness of the π states of C$_{60}$ that are preserved after Co trapping. Scanning tunneling microscopy images and density functional theory calculations reveal that dissociated Co clusters of up to nine atoms can be formed at the molecule−substrate interface. These results open new perspectives in the interactions between metal adatoms and molecules, for applications in metal−organic devices.
Published: 2015
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19. 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
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20. Tuning the Magnetic Anisotropy at a Molecule-Metal Interface

Author: Cyrille Barreteau, R. Breitwieser, Cyril Chacon, Y. Chao, Yu-Cheng Hu, Amandine Bellec, Vincent Repain, Yves Garreau, Sylvie Rousset, Dongzhe Li, Woei Wu Pai, Yann Girard, Jérôme Lagoute, Alexander Smogunov, Kaushik Bairagi, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), National Taiwan University [Taiwan] (NTU), 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), 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, DTU Nanotech, Danmarks Tekniske Universitet = Technical University of Denmark (DTU), The ab initio calculations were performed using HPC resources from GENCI- [TGCC/IDRIS] (Grants No. 2014096813 and No. 2015097416), ANR-12-BS10-0006,SPIROU,Magnéto-résistance de nano-objets moléculaires(2012), European Project: 259297,EC:FP7:ERC,ERC-2010-StG_20091028,MAGNETALS(2010), 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), and Technical University of Denmark [Lyngby] (DTU)
Subjects: 7530Gw, [PHYS]Physics [physics], Materials science, Condensed matter physics, General Physics and Astronomy, 7320Hb, Overlayer, Magnetic anisotropy, 7820Ls, Atomic orbital, Ab initio quantum chemistry methods, Molecule, Thin film, Anisotropy, Spin (physics), 7570Cn
Abstract: We demonstrate that a C60 overlayer enhances the perpendicular magnetic anisotropy of a Co thin film, inducing an inverse spin reorientation transition from in plane to out of plane. The driving force is the C60/Co interfacial magnetic anisotropy that we have measured quantitatively in situ as a function of the C60 coverage. Comparison with state-of-the-art ab initio calculations show that this interfacial anisotropy mainly arises from the local hybridization between C60 pz and Co dz2 orbitals. By generalizing these arguments, we also demonstrate that the hybridization of C60 with a Fe(110) surface decreases the perpendicular magnetic anisotropy. These results open the way to tailor the interfacial magnetic anisotropy in organic-material-ferromagnet systems.
Published: 2015
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21. 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
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22. 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
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23. 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
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24. Directed Growth of Mixed Self-Assembled Monolayers on a Nanostructured Template: a Step toward the Patterning of Functional Molecular Domains

Author: S. Rousset, Paolo Campiglio, Philippe Lang, Nicolas Battaglini, Cyril Chacon, Z. Qin, V. Repain, Interfaces, Traitements, Organisation et Dynamique des Systèmes (ITODYS (UMR_7086)), Université Paris Diderot - Paris 7 (UPD7)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire catalyse et spectrochimie (LCS), 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), Normandie Université (NU), Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), University of St Andrews [Scotland], Knoop, Martina, Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), 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), and University of St Andrews
Subjects: [PHYS]Physics [physics], Materials science, chemistry.chemical_element, Biasing, Self-assembled monolayer, Nanotechnology, 02 engineering and technology, Surfaces and Interfaces, 010402 general chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, 0104 chemical sciences, [PHYS] Physics [physics], chemistry.chemical_compound, Terthiophene, chemistry, Chemical affinity, Electrochemistry, Molecule, General Materials Science, 0210 nano-technology, Cobalt, Spectroscopy, Quantum tunnelling
Abstract: We report on the elaboration of networks of SAM domains. More precisely, we show the feasibility in making arrays of functionalized alkylthiol nanodomains bordered with an alkylthiol matrix. The several step process relies on the replication of a self-organized cobalt array grown on Au(111). The SAM process takes place in solution. The chemical affinity of thiol for gold leads to the selective grafting of molecules on the surface. After having removed the inorganic array, alkylthiol functionalized with a terthiophene unit is grafted in free gold areas. The efficiency of the replication of the initial template depends on the stability of the first SAM. We also investigate electronic tunnel transport through oligothiophene islands with the STM. The variation of the molecular contrast with bias voltage between the two molecular species indicates a potential resonant tunneling mechanism through the orbitals of the aromatic compound.
Published: 2012

25. 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

26. 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

27. 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
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28. 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

29. 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

30. 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

31. 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
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32. Perpendicular magnetocrystalline anisotropy in tetragonally distorted Fe-Co alloys

Author: Lars Nordström, Biplab Sanyal, Till Burkert, Olle Eriksson, Claudia Zlotea, Cyril Chacon, Per Nordblad, Peter Warnicke, Matts Björck, and Gabriella Andersson
Subjects: Materials science, Condensed matter physics, Superlattice, General Physics and Astronomy, Magnetocrystalline anisotropy, Condensed Matter Physics, Storage material, Tetragonal crystal system, Magnetic anisotropy, Condensed Matter::Materials Science, Distortion, Teknik och teknologier, Atom, Perpendicular, Engineering and Technology, Den kondenserade materiens fysik
Abstract: We report on the experimental realization of tetragonal Fe-Co alloys as a constituent of Fe0.36Co0.64/Pt superlattices with huge perpendicular magnetocrystalline anisotropy energy, reaching 210µeV/atom, and a saturation magnetization of 2.5µB/atom at 40 K, in qualitative agreement with theoretical predictions. At room temperature the corresponding values 150µeV/atom and 2.2µB/atom are achieved. This suggests that Fe-Co alloys with carefully chosen combinations of composition and distortion are good candidates for high-density perpendicular storage materials. © 2006 The American Physical Society.
Published: 2006

33. Anomalous Light‐Induced Spin‐State Switching for Iron(II) Spin‐Crossover Molecules in Direct Contact with Metal Surfaces

Author: Massine Kelai, Sylvie Rousset, Cyril Chacon, Philippe Sainctavit, Edwige Otero, Luqiong Zhang, Vincent Repain, Amandine Bellec, Yongfeng Tong, Marie-Laure Boillot, M.-A. Arrio, Talal Mallah, Yann Girard, Eric Rivière, Jérôme Lagoute, 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), 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), Université Paris-Sud - Paris 11 (UP11)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), European Project: 766726,211587,COSMICS(2017), Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), 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, 02 engineering and technology, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010402 general chemistry, Molecular physics, 01 natural sciences, Catalysis, LIESST, Spin crossover, [CHIM.COOR]Chemical Sciences/Coordination chemistry, ComputingMilieux_MISCELLANEOUS, Valence (chemistry), 010405 organic chemistry, General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, General Medicine, Photoelectric effect, 021001 nanoscience & nanotechnology, 0104 chemical sciences, X-ray Absorption Spectroscopy, Spin-Crossover, Molecule / metal interface, Excited state, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Condensed Matter::Strongly Correlated Electrons, Light induced transition, 0210 nano-technology, Excitation, Visible spectrum
Abstract: Light‐induced spin‐state switching is one of the most attractive properties of spin‐crossover materials. In bulk, low‐spin (LS) to high‐spin (HS) conversion via the light‐induced excited spin‐state trapping (LIESST) effect may be achieved with a visible light, while the HS‐to‐LS one (reverse‐LIESST) requires an excitation in the near‐infrared range. Now, it is shown that those phenomena are strongly modified at the interface with a metal. Indeed, an anomalous spin conversion is presented from HS state to LS state under blue light illumination for FeII spin‐crossover molecules that are in direct contact with metallic (111) single‐crystal surfaces (copper, silver, and gold). To interpret this anomalous spin‐state switching, a new mechanism is proposed for the spin conversion based on the light absorption by the substrate that can generate low energy valence photoelectrons promoting molecular vibrational excitations and subsequent spin‐state switching at the molecule–metal interface.
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34. Evidence of a C 60 /Co interface reconstruction and its influence on magnetic properties

Author: Cynthia Fourmental, Ludovic Le Laurent, Vincent Repain, Cyril Chacon, Yann Girard, Jérôme Lagoute, Sylvie Rousset, Alessandro Coati, Yves Garreau, Andrea Resta, Alina Vlad, Cyrille Barreteau, Alexander Smogunov, Dongzhe Li, Amandine Bellec, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), 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, Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Centre d'élaboration de matériaux et d'études structurales (CEMES), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées (INSA)-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), European Project: 766726,211587,COSMICS(2017), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 02 engineering and technology, 021001 nanoscience & nanotechnology, 010306 general physics, 0210 nano-technology, 01 natural sciences
Abstract: International audience; By using grazing incidence x-ray diffraction and scanning tunneling microscopy experiments, we determine the interface structure of a C 60 layer deposited on a Co(0001) surface. The room temperature deposition gives rise to a (4 × 4) molecular structure with a 10% vertical relaxation of the underneath Co atoms. When annealed around 550 K, the interface undergoes a structural change with most of the buckyballs sitting in a seven Co vacancies nanohole. Ab initio calculations show that this interface reconstruction is stabilized by a strong C-Co hybridization and has a significant impact both on the interfacial magnetic anisotropy that is decreased and on the molecular spin polarization that it increased.
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34 results on '"Cyril Chacon"'

1. Higher-indexed Moiré patterns and surface states of MoTe2/graphene heterostructure grown by molecular beam epitaxy

2. Quantum Transport in Large-Scale Patterned Nitrogen-Doped Graphene

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

4. Change of cobalt magnetic anisotropy and spin polarization with alkanethiolates self-assembled monolayers

5. Growth and local electronic properties of Cobalt nanodots underneath graphene on SiC(0001)

6. Visualizing In-Plane Junctions in Nitrogen-Doped Graphene

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

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

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

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

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

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

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

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

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

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

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

18. C$_{60}$ as an Atom Trap to Capture Co Adatoms

19. Electronic interaction between nitrogen atoms in doped graphene

20. Tuning the Magnetic Anisotropy at a Molecule-Metal Interface

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

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

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

24. Directed Growth of Mixed Self-Assembled Monolayers on a Nanostructured Template: a Step toward the Patterning of Functional Molecular Domains

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

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

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

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

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

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

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

32. Perpendicular magnetocrystalline anisotropy in tetragonally distorted Fe-Co alloys

33. Anomalous Light‐Induced Spin‐State Switching for Iron(II) Spin‐Crossover Molecules in Direct Contact with Metal Surfaces

34. Evidence of a C 60 /Co interface reconstruction and its influence on magnetic properties

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34 results on '"Cyril Chacon"'

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