Search

Your search keyword '"Céline Vergnaud"' showing total 22 results
Start Over Author "Céline Vergnaud"
22 results on '"Céline Vergnaud"'

1. Effect of crystallinity and thickness on thermal transport in layered PtSe2

Author

Alexandros El Sachat, Peng Xiao, Davide Donadio, Frédéric Bonell, Marianna Sledzinska, Alain Marty, Céline Vergnaud, Hervé Boukari, Matthieu Jamet, Guillermo Arregui, Zekun Chen, Francesc Alzina, Clivia M. Sotomayor Torres, and Emigdio Chavez-Angel

Subjects
Materials of engineering and construction. Mechanics of materials, TA401-492, Chemistry, QD1-999
Abstract

Abstract We present a comparative investigation of the influence of crystallinity and film thickness on the acoustic and thermal properties of layered PtSe2 films of varying thickness (1–40 layers) using frequency-domain thermo-reflectance, low-frequency Raman, and pump-probe coherent phonon spectroscopy. We find ballistic cross-plane heat transport up to ~30 layers PtSe2 and a 35% reduction in the cross-plane thermal conductivity of polycrystalline films with thickness larger than 20 layers compared to the crystalline films of the same thickness. First-principles calculations further reveal a high degree of thermal conductivity anisotropy and a remarkable large contribution of the optical phonons to the thermal conductivity in bulk (~20%) and thin PtSe2 films (~30%). Moreover, we show strong interlayer interactions in PtSe2, short acoustic phonon lifetimes in the range of picoseconds, an out-of-plane elastic constant of 31.8 GPa, and a layer-dependent group velocity ranging from 1340 ms−1 in bilayer to 1873 ms−1 in eight layers of PtSe2. The potential of tuning the lattice thermal conductivity of layered materials with the level of crystallinity and the real-time observation of coherent phonon dynamics open a new playground for research in 2D thermoelectric devices and provides guidelines for thermal management in 2D electronics.

Published
2022
Full Text
View/download PDF

2. Large-scale epitaxy of two-dimensional van der Waals room-temperature ferromagnet Fe5GeTe2

Author

Mário Ribeiro, Giulio Gentile, Alain Marty, Djordje Dosenovic, Hanako Okuno, Céline Vergnaud, Jean-François Jacquot, Denis Jalabert, Danilo Longo, Philippe Ohresser, Ali Hallal, Mairbek Chshiev, Olivier Boulle, Frédéric Bonell, and Matthieu Jamet

Subjects
Materials of engineering and construction. Mechanics of materials, TA401-492, Chemistry, QD1-999
Abstract

Abstract In recent years, two-dimensional van der Waals materials have emerged as an important platform for the observation of long-range ferromagnetic order in atomically thin layers. Although heterostructures of such materials can be conceived to harness and couple a wide range of magneto-optical and magneto-electrical properties, technologically relevant applications require Curie temperatures at or above room temperature and the ability to grow films over large areas. Here we demonstrate the large-area growth of single-crystal ultrathin films of stoichiometric Fe5GeTe2 on an insulating substrate using molecular beam epitaxy. Magnetic measurements show the persistence of soft ferromagnetism up to room temperature in 12 nm-thick films, with a Curie temperature of 293 K, and a weak out-of-plane magnetocrystalline anisotropy. The ferromagnetic order is preserved in bilayer Fe5GeTe2, with Curie temperature decreasing to 229 K. Surface, chemical, and structural characterizations confirm the layer-by-layer growth, 5:1:2 Fe:Ge:Te stoichiometric elementary composition, and single-crystalline character of the films.

Published
2022
Full Text
View/download PDF

3. Control of spin–charge conversion in van der Waals heterostructures

Author

Regina Galceran, Bo Tian, Junzhu Li, Frédéric Bonell, Matthieu Jamet, Céline Vergnaud, Alain Marty, Jose H. García, Juan F. Sierra, Marius V. Costache, Stephan Roche, Sergio O. Valenzuela, Aurélien Manchon, Xixiang Zhang, and Udo Schwingenschlögl

Subjects
Biotechnology, TP248.13-248.65, Physics, QC1-999
Abstract

The interconversion between spin and charge degrees of freedom offers incredible potential for spintronic devices, opening routes for spin injection, detection, and manipulation alternative to the use of ferromagnets. The understanding and control of such interconversion mechanisms, which rely on spin–orbit coupling, is therefore an exciting prospect. The emergence of van der Waals materials possessing large spin–orbit coupling (such as transition metal dichalcogenides or topological insulators) and/or recently discovered van der Waals layered ferromagnets further extends the possibility of spin-to-charge interconversion to ultrathin spintronic devices. Additionally, they offer abundant room for progress in discovering and analyzing novel spin–charge interconversion phenomena. Modifying the properties of van der Waals materials through proximity effects is an added degree of tunability also under exploration. This Perspective discusses the recent advances toward spin-to-charge interconversion in van der Waals materials. It highlights scientific developments which include techniques for large-scale growth, device physics, and theoretical aspects.

Published
2021
Full Text
View/download PDF

4. The valley Nernst effect in WSe2

Author

Minh Tuan Dau, Céline Vergnaud, Alain Marty, Cyrille Beigné, Serge Gambarelli, Vincent Maurel, Timotée Journot, Bérangère Hyot, Thomas Guillet, Benjamin Grévin, Hanako Okuno, and Matthieu Jamet

Subjects
Science
Abstract

Atomically thin transition metal dichalcogenides possess a valley degree of freedom, which could enrich the physics underpinning the conventional Nernst effect observed in traditional solids. Here, the authors report experimental evidence of the valley Nernst effect in WSe2 at room temperature.

Published
2019
Full Text
View/download PDF

5. Visualizing Giant Ferroelectric Gating Effects in Large-Scale WSe2/BiFeO3 Heterostructures

Author

Raphaël Salazar, Sara Varotto, Céline Vergnaud, Vincent Garcia, Stéphane Fusil, Julien Chaste, Thomas Maroutian, Alain Marty, Frédéric Bonell, Debora Pierucci, Abdelkarim Ouerghi, François Bertran, Patrick Le Fèvre, Matthieu Jamet, Manuel Bibes, Julien Rault, Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Unité mixte de physique CNRS/Thales (UMPhy CNRS/THALES), THALES [France]-Centre National de la Recherche Scientifique (CNRS), SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), Centre de Nanosciences et de Nanotechnologies (C2N), Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire de photonique et de nanostructures (LPN), ANR-18-CE24-0007,MAGICVALLEY,Polarisation de vallée induite par couplage d'échange magnétique dans les matériaux 2D à grande échelle(2018), and ANR-18-CE24-0015,CORNFLAKE,Contrôle ferroélectrique du couplage spin-orbite dans les dichalcogenides de métaux de transition(2018)

Subjects
perovskite oxides, Condensed Matter - Materials Science, Strongly Correlated Electrons (cond-mat.str-el), quantum materials, Mechanical Engineering, ferroelectrics, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, Bioengineering, General Chemistry, Condensed Matter Physics, Condensed Matter - Strongly Correlated Electrons, heterostructures, transition-metal dichalcogenides, General Materials Science, angle-resolved photoemission spectroscopy, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat]
Abstract

International audience; Multilayers based on quantum materials (complex oxides, topological insulators, transition-metal dichalcogenides, etc.) have enabled the design of devices that could revolutionize microelectronics and optoelectronics. However, heterostructures incorporating quantum materials from different families remain scarce, while they would immensely broaden the range of possible applications. Here we demonstrate the large-scale integration of compounds from two highly multifunctional families: perovskite oxides and transition-metal dichalcogenides (TMDs). We couple BiFeO 3 , a room-temperature multiferroic oxide, and WSe 2 , a semiconducting two-dimensional material with potential for photovoltaics and photonics. WSe 2 is grown by molecular beam epitaxy and transferred on a centimeter-scale onto BiFeO 3 films. Using angle-resolved photoemission spectroscopy, we visualize the electronic structure of 1 to 3 monolayers of WSe 2 and evidence a giant energy shift as large as 0.75 eV induced by the ferroelectric polarization direction in the underlying BiFeO 3. Such a strong shift opens new perspectives in the efficient manipulation of TMD properties by proximity effects.

Published
2022
Full Text
View/download PDF

6. Epitaxial van der Waals heterostructures of Cr2Te3 on two-dimensional materials

Author

Quentin Guillet, Libor Vojáček, Djordje Dosenovic, Fatima Ibrahim, Hervé Boukari, Jing Li, Fadi Choueikani, Philippe Ohresser, Abdelkarim Ouerghi, Florie Mesple, Vincent Renard, Jean-François Jacquot, Denis Jalabert, Hanako Okuno, Mairbek Chshiev, Céline Vergnaud, Frédéric Bonell, Alain Marty, and Matthieu Jamet

Subjects
Physics and Astronomy (miscellaneous), General Materials Science
Published
2023
Full Text
View/download PDF

7. The search for manganese incorporation in MoSe 2 monolayer epitaxially grown on graphene

Author

Maxime Gay, Minh-Tuan Dau, Céline Vergnaud, Alain Marty, Frédéric Bonell, Hervé Boukari, Colin Paillet, Bérangère Hyot, Hanako Okuno, Pierre Mallet, Jean-Yves Veuillen, Olivier Renault, Matthieu Jamet, Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), Nanophysique et Semiconducteurs (NPSC), Institut Néel (NEEL), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Nano-Electronique Quantique et Spectroscopie (QuNES), ANR-18-CE24-0007,MAGICVALLEY,Polarisation de vallée induite par couplage d'échange magnétique dans les matériaux 2D à grande échelle(2018), ANR-10-LABX-0051,LANEF,Laboratory of Alliances on Nanosciences - Energy for the Future(2010), Nanophysique et Semiconducteurs (NEEL - NPSC), and Nano-Electronique Quantique et Spectroscopie (NEEL - QuNES)

Subjects
Materials science, Graphene, General Physics and Astronomy, chemistry.chemical_element, 02 engineering and technology, Manganese, 2D materials, 021001 nanoscience & nanotechnology, Epitaxy, 01 natural sciences, law.invention, Crystallography, chemistry, law, 0103 physical sciences, Monolayer, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Magnetic doping, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Scanning tunneling microscopy, 010306 general physics, 0210 nano-technology, Molecular beam epitaxy, Transmission electron microscopy, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2022
Full Text
View/download PDF

8. Ferromagnetism and Rashba Spin–Orbit Coupling in the Two-Dimensional (V,Pt)Se2 Alloy

Author

Emilio Vélez-Fort, Ali Hallal, Roberto Sant, Thomas Guillet, Khasan Abdukayumov, Alain Marty, Céline Vergnaud, Jean-François Jacquot, Denis Jalabert, Jun Fujii, Ivana Vobornik, Julien Rault, Nicholas B. Brookes, Danilo Longo, Philippe Ohresser, Abdelkarim Ouerghi, Jean-Yves Veuillen, Pierre Mallet, Hervé Boukari, Hanako Okuno, Mairbek Chshiev, Frédéric Bonell, Matthieu Jamet, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), European Synchrotron Radiation Facility (ESRF), Conception d’Architectures Moléculaires et Processus Electroniques (CAMPE ), SYstèmes Moléculaires et nanoMatériaux pour l’Energie et la Santé (SYMMES), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Département Interfaces pour l'énergie, la Santé et l'Environnement (DIESE), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Laboratorio TASC (IOM CNR), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), CNR Istituto Officina dei Materiali (IOM), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Centre de Nanosciences et de Nanotechnologies (C2N), Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Nano-Electronique Quantique et Spectroscopie (NEEL - QuNES), Institut Néel (NEEL), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Nanophysique et Semiconducteurs (NEEL - NPSC), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), ANR-18-CE24-0007,MAGICVALLEY,Polarisation de vallée induite par couplage d'échange magnétique dans les matériaux 2D à grande échelle(2018), ANR-10-LABX-0051,LANEF,Laboratory of Alliances on Nanosciences - Energy for the Future(2010), and European Project: 785219,H2020,GrapheneCore2(2018)

Subjects
Condensed Matter::Materials Science, Materials Chemistry, Electrochemistry, Condensed Matter::Strongly Correlated Electrons, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, Electronic, Optical and Magnetic Materials
Abstract

5 pages, 5 figures; International audience; We report on a two-dimensional (2D) V1–xPtxSe2 alloy that exhibits ferromagnetic order and Rashba spin–orbit coupling. Although ferromagnetism is absent in 1T-VSe2 because of the competition with the charge density wave phase, we demonstrate theoretically and experimentally that the substitution of vanadium by platinum in VSe2 (10–50%) to form a homogeneous 2D alloy restores ferromagnetic order down to one monolayer of V0.65Pt0.35Se2. Moreover, the presence of platinum atoms gives rise to Rashba spin–orbit coupling in (V,Pt)Se2, providing an original platform to study the interplay between ferromagnetism and spin–orbit coupling in the 2D limit.

Published
2022
Full Text
View/download PDF

9. Hybridization and localized flat band in the WSe2/MoSe2 heterobilayer

Author

Lama Khalil, Debora Pierucci, Emilio Velez-Fort, José Avila, Céline Vergnaud, Pavel Dudin, Fabrice Oehler, Julien Chaste, Matthieu Jamet, Emmanuel Lhuillier, Marco Pala, Abdelkarim Ouerghi, Centre de Nanosciences et de Nanotechnologies (C2N), Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Physico-chimie et dynamique des surfaces (INSP-E6), Institut des Nanosciences de Paris (INSP), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), ANR-17-CE24-0030,RhomboG,Propriétés electroniques de couches minces de graphite rhombohedrique(2017), ANR-18-CE24-0007,MAGICVALLEY,Polarisation de vallée induite par couplage d'échange magnétique dans les matériaux 2D à grande échelle(2018), ANR-19-CE09-0026,GRaSkop,Tuning Giant Rashba Spin-Orbit Coupling in Polar Single Layer Transition Metal Dichalcogenides(2019), and ANR-10-LABX-0035,Nano-Saclay,Paris-Saclay multidisciplinary Nano-Lab(2010)

Subjects
perovskite oxides, [PHYS]Physics [physics], MBE, Mechanical Engineering, quantum materials, ferroelectrics, Bioengineering, General Chemistry, 2D materials, heterostructures, Mechanics of Materials, transition-metal dichalcogenides, General Materials Science, Electrical and Electronic Engineering, angle-resolved photoemission spectroscopy, XPS/ARPES, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat]
Abstract

Nearly localized moiré flat bands in momentum space, arising at particular twist angles, are the key to achieve correlated effects in transition-metal dichalcogenides. Here, we use angle-resolved photoemission spectroscopy (ARPES) to visualize the presence of a flat band near the Fermi level of van der Waals WSe2/MoSe2 heterobilayer grown by molecular beam epitaxy. This flat band is localized near the Fermi level and has a width of several hundred meVs. By combining ARPES measurements with density functional theory calculations, we confirm the coexistence of different domains, namely the reference 2H stacking without layer misorientation and regions with arbitrary twist angles. For the 2H-stacked heterobilayer, our ARPES results show strong interlayer hybridization effects, further confirmed by complementary micro- Raman spectroscopy measurements. The spin-splitting of the valence band at K is determined to be 470 meV. The valence band maximum (VBM) position of the heterobilayer is located at the Γ point. The energy difference between the VBM at Γ and the K point is of −60 meV, which is a stark difference compared to individual single monolayer WSe2 and monolayer WSe2, showing both a VBM at K.

Published
2023
Full Text
View/download PDF

10. Evidence for highly p-type doping and type II band alignment in large scale monolayer WSe2/Se-terminated GaAs heterojunction grown by molecular beam epitaxy

Author

Debora Pierucci, Aymen Mahmoudi, Mathieu Silly, Federico Bisti, Fabrice Oehler, Gilles Patriarche, Frédéric Bonell, Alain Marty, Céline Vergnaud, Matthieu Jamet, Hervé Boukari, Emmanuel Lhuillier, Marco Pala, Abdelkarim Ouerghi, Centre de Nanosciences et de Nanotechnologies (C2N), Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Dipartimento di Scienze Fisiche e Chimiche [L'Aquila], Università degli Studi dell'Aquila = University of L'Aquila (UNIVAQ), SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), Nanophysique et Semiconducteurs (NEEL - NPSC), Institut Néel (NEEL), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Institut des Nanosciences de Paris (INSP), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), ANR-17-CE24-0030,RhomboG,Propriétés electroniques de couches minces de graphite rhombohedrique(2017), ANR-18-CE24-0007,MAGICVALLEY,Polarisation de vallée induite par couplage d'échange magnétique dans les matériaux 2D à grande échelle(2018), ANR-19-CE09-0026,GRaSkop,Tuning Giant Rashba Spin-Orbit Coupling in Polar Single Layer Transition Metal Dichalcogenides(2019), and ANR-10-LABX-0051,LANEF,Laboratory of Alliances on Nanosciences - Energy for the Future(2010)

Subjects
Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, General Materials Science, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat]
Abstract

International audience; Two-dimensional materials (2D) arranged in hybrid van der Waals (vdW) heterostructures provide a route toward the assembly of 2D and conventional III–V semiconductors. Here{,} we report the structural and electronic properties of single layer WSe2 grown by molecular beam epitaxy on Se-terminated GaAs(111)B. Reflection high-energy electron diffraction images exhibit sharp streaky features indicative of a high-quality WSe2 layer produced via vdW epitaxy. This is confirmed by in-plane X-ray diffraction. The single layer of WSe2 and the absence of interdiffusion at the interface are confirmed by high resolution X-ray photoemission spectroscopy and high-resolution transmission microscopy. Angle-resolved photoemission investigation revealed a well-defined WSe2 band dispersion and a high p-doping coming from the charge transfer between the WSe2 monolayer and the Se-terminated GaAs substrate. By comparing our results with local and hybrid functionals theoretical calculation{,} we find that the top of the valence band of the experimental heterostructure is close to the calculations for free standing single layer WSe2. Our experiments demonstrate that the proximity of the Se-terminated GaAs substrate can significantly tune the electronic properties of WSe2. The valence band maximum (VBM{,} located at the K point of the Brillouin zone) presents an upshift of about 0.56 eV toward the Fermi level with respect to the VBM of the WSe2 on graphene layer{,} which is indicative of high p-type doping and a key feature for applications in nanoelectronics and optoelectronics.

Published
2022
Full Text
View/download PDF

11. Large-scale epitaxy of two-dimensional van der Waals room-temperature ferromagnet Fe5GeTe2

Author

Mário Ribeiro, Giulio Gentile, Alain Marty, Djordje Dosenovic, Hanako Okuno, Céline Vergnaud, Jean-François Jacquot, Denis Jalabert, Danilo Longo, Philippe Ohresser, Ali Hallal, Mairbek Chshiev, Olivier Boulle, Frédéric Bonell, Matthieu Jamet, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Conception d’Architectures Moléculaires et Processus Electroniques (CAMPE ), SYstèmes Moléculaires et nanoMatériaux pour l’Energie et la Santé (SYMMES), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Département Interfaces pour l'énergie, la Santé et l'Environnement (DIESE), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), ANR-18-CE24-0007,MAGICVALLEY,Polarisation de vallée induite par couplage d'échange magnétique dans les matériaux 2D à grande échelle(2018), ANR-20-CE24-0015,ELMAX,Contrôle électrique de l'aimantation dans les hétérostructures van der Waals épitaxiées(2020), ANR-10-LABX-0051,LANEF,Laboratory of Alliances on Nanosciences - Energy for the Future(2010), ANR-15-IDEX-0002,UGA,IDEX UGA(2015), Institut de Chimie du CNRS (INC)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Condensed Matter - Materials Science, Condensed Matter::Materials Science, Mechanics of Materials, Mechanical Engineering, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, General Materials Science, General Chemistry, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Condensed Matter Physics
Abstract

In recent years, two-dimensional van der Waals materials have emerged as an important platform for the observation of long-range ferromagnetic order in atomically thin layers. Although heterostructures of such materials can be conceived to harness and couple a wide range of magneto-optical and magneto-electrical properties, technologically relevant applications require Curie temperatures at or above room temperature and the ability to grow films over large areas. Here we demonstrate the large-area growth of single-crystal ultrathin films of stoichiometric Fe5GeTe2 on an insulating substrate using molecular beam epitaxy. Magnetic measurements show the persistence of soft ferromagnetism up to room temperature in 12 nm-thick films, with a Curie temperature of 293 K, and a weak out-of-plane magnetocrystalline anisotropy. The ferromagnetic order is preserved in bilayer Fe5GeTe2, with Curie temperature decreasing to 229 K. Surface, chemical, and structural characterizations confirm the layer-by-layer growth, 5:1:2 Fe:Ge:Te stoichiometric elementary composition, and single-crystalline character of the films.

Published
2021
Full Text
View/download PDF

12. High carrier mobility in single-crystal PtSe2 grown by molecular beam epitaxy on ZnO(0001)

Author

Alain Marty, Frédéric Bonell, Vincent Consonni, Hervé Boukari, Matthieu Jamet, Céline Vergnaud, Hanako Okuno, Abdelkarim Ouerghi, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), and ANR-20-CE24-0015,ELMAX,Contrôle électrique de l'aimantation dans les hétérostructures van der Waals épitaxiées(2020)

Subjects
Electron mobility, Materials science, FOS: Physical sciences, 02 engineering and technology, 010402 general chemistry, Epitaxy, 01 natural sciences, law.invention, law, General Materials Science, [PHYS]Physics [physics], Condensed Matter - Materials Science, Spintronics, business.industry, Graphene, Mechanical Engineering, Materials Science (cond-mat.mtrl-sci), General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 0104 chemical sciences, Mechanics of Materials, Transmission electron microscopy, Sapphire, Optoelectronics, 0210 nano-technology, business, Single crystal, Molecular beam epitaxy
Abstract

PtSe2 is attracting considerable attention as a high mobility two-dimensional material with envisioned applications in microelectronics, photodetection and spintronics. The growth of high quality PtSe2 on insulating substrates with wafer-scale uniformity is a prerequisite for electronic transport investigations and practical use in devices. Here, we report the growth of highly oriented few-layers PtSe2 on ZnO(0001) by molecular beam epitaxy. The crystalline structure of the films is characterized with electron and x-ray diffraction, atomic force microscopy and transmission electron microscopy. The comparison with PtSe2 layers grown on graphene, sapphire, mica, SiO2 and Pt(111) shows that among insulating substrates, ZnO(0001) yields films of superior structural quality. Hall measurements performed on epitaxial ZnO/PtSe2 with five monolayers of PtSe2 show a clear semiconducting behaviour and a high mobility in excess of 200 cm2 V−1 s−1 at room temperature and up to 447 cm2 V−1 s−1 at low temperature.

Published
2021
Full Text
View/download PDF

13. New approach for the molecular beam epitaxy growth of scalable WSe

Author

Céline, Vergnaud, Minh-Tuan, Dau, Benjamin, Grévin, Christophe, Licitra, Alain, Marty, Hanako, Okuno, and Matthieu, Jamet

Abstract

The search for high-quality transition metal dichalcogenides mono- and multi-layers grown on large areas is still a very active field of investigation. Here, we use molecular beam epitaxy to grow WSe

Published
2020

14. Van der Waals solid phase epitaxy to grow large-area manganese-doped MoSe$_2$ few-layers on SiO$_2$/Si

Author

Céline Vergnaud, Maxime Gay, Carlos Alvarez, Minh-Tuan Dau, François Pierre, Denis Jalabert, Christophe Licitra, Alain Marty, Cyrille Beigné, Benjamin Grévin, Olivier Renault, Hanako Okuno, Matthieu Jamet, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Laboratoire d'Etude des Matériaux par Microscopie Avancée (LEMMA ), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), SYstèmes Moléculaires et nanoMatériaux pour l’Energie et la Santé (SYMMES), Institut de Chimie du CNRS (INC)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Synthèse, Structure et Propriétés de Matériaux Fonctionnels (STEP), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), CEA-project 2D FACTORY, Agence Nationale de la Recherche within the ANR MoS2ValleyControl project [ANR-14-CE26-0017], CEA-project 2D FACTORY, Agence Nationale de la Recherche within the ANR MAGICVALLEY project, French state funds LANEF [ANR-10-LABX-51-01], 'Recherches Technologiques de Base' Program of the French Ministry of Research, CEA-Enhanced Eurotalents program, ANR-14-CE26-0017,MoS2ValleyControl,Propriétés optiques et de transport dans des mono-couches de MoS2 et discpositifs associés(2014), ANR-18-CE24-0007,MAGICVALLEY,Polarisation de vallée induite par couplage d'échange magnétique dans les matériaux 2D à grande échelle(2018), ANR-10-LABX-0051,LANEF,Laboratory of Alliances on Nanosciences - Energy for the Future(2010), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG)

Subjects
Materials science, FOS: Physical sciences, 02 engineering and technology, 010402 general chemistry, Epitaxy, 01 natural sciences, large-scale growth, symbols.namesake, [SPI]Engineering Sciences [physics], Monolayer, General Materials Science, Thin film, solid phase epitaxy, structural properties, Condensed Matter - Materials Science, van der Waals epitaxy, Mechanical Engineering, Doping, transition metal dichalcogenides, Materials Science (cond-mat.mtrl-sci), General Chemistry, Magnetic semiconductor, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 0104 chemical sciences, Amorphous solid, manganese doping, Mechanics of Materials, Chemical physics, symbols, electronic properties, van der Waals force, 0210 nano-technology, Molecular beam epitaxy
Abstract

Large-area growth of continuous transition metal dichalcogenides (TMDCs) layers is a prerequisite to transfer their exceptional electronic and optical properties into practical devices. It still represents an open issue nowadays. Electric and magnetic doping of TMDC layers to develop basic devices such as p-n junctions or diluted magnetic semiconductors for spintronic applications are also an important field of investigation. Here, we have developed two different techniques to grow MoSe$_2$ mono- and multi-layers on SiO$_2$/Si substrates over large areas. First, we co-deposited Mo and Se atoms on SiO$_2$/Si by molecular beam epitaxy in the van der Waals regime to obtain continuous MoSe$_2$ monolayers over 1 cm$^2$. To grow MoSe$_2$ multilayers, we then used the van der Waals solid phase epitaxy which consists in depositing an amorphous Se/Mo bilayer on top of a co-deposited MoSe$_2$ monolayer which serves as a van der Waals growth template. By annealing, we obtained continuous MoSe$_2$ multilayers over 1 cm$^2$. Moreover, by inserting a thin layer of Mn in the stack, we could demonstrate the incorporation of up to 10 \% of Mn in MoSe$_2$ bilayers., 32 pages, 13 figures

Published
2019
Full Text
View/download PDF

15. Toward efficient spin/charge conversion using topological insulator surface (Conference Presentation)

Author

Albert Fert, Céline Vergnaud, Patrick Lefèvre, Henri Jaffrès, Alain Marty, Nicolas Reyren, Laurent Vila, François Bertran, Paul Noël, A. Taleb-Ibrahimi, Q. Barbedienne, Jean-Marie George, Aristide Lemaître, Julien Varignon, Unité mixte de physique CNRS/Thales (UMPhy CNRS/THALES), THALES [France]-Centre National de la Recherche Scientifique (CNRS), SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Centre de Nanosciences et de Nanotechnologies (C2N), and Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Surface (mathematics), Condensed matter physics, Topological insulator, Charge (physics), [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Spin-½
Abstract

International audience

Published
2018
Full Text
View/download PDF

16. Beyond van der Waals Interaction: The Case of MoSe$_2$ Epitaxially Grown on Few-Layer Graphene

Author

Minh Tuan Dau, Maxime Gay, Daniela Di Felice, Céline Vergnaud, Alain Marty, Cyrille Beigné, Gilles Renaud, Olivier Renault, Pierre Mallet, Toai Le Quang, Jean-Yves Veuillen, Loïc Huder, Vincent T. Renard, Claude Chapelier, Giovanni Zamborlini, Matteo Jugovac, Vitaliy Feyer, Yannick J. Dappe, Pascal Pochet, Matthieu Jamet, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), 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), Nanostructures et Rayonnement Synchrotron (NRS ), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Nano-Electronique Quantique et Spectroscopie (QuNES), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Laboratoire de Transport Electronique Quantique et Supraconductivité (LaTEQS), PHotonique, ELectronique et Ingénierie QuantiqueS (PHELIQS), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Forschungszentrum Jülich GmbH | Centre de recherche de Juliers, Helmholtz-Gemeinschaft = Helmholtz Association, Laboratory of Atomistic Simulation (LSIM ), ANR-14-CE26-0017,MoS2ValleyControl,Propriétés optiques et de transport dans des mono-couches de MoS2 et discpositifs associés(2014), ANR-11-EQPX-0010,CRGF,Lignes synchrotron françaises à l'ESRF(2011), ANR-10-LABX-0051,LANEF,Laboratory of Alliances on Nanosciences - Energy for the Future(2010), European Project: 604391,EC:FP7:ICT,FP7-ICT-2013-FET-F,GRAPHENE(2013), 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, and Nano-Electronique Quantique et Spectroscopie (NEEL - QuNES)

Subjects
Materials science, heterojunction, Band gap, General Physics and Astronomy, 02 engineering and technology, MoSe2, Epitaxy, 01 natural sciences, Electron spectroscopy, law.invention, symbols.namesake, law, 0103 physical sciences, Physics::Atomic and Molecular Clusters, band-gap opening, General Materials Science, 010306 general physics, Electronic band structure, [PHYS]Physics [physics], Condensed matter physics, Graphene, General Engineering, charge transfer, Heterojunction, commensurability, 021001 nanoscience & nanotechnology, few-layer graphene, van der Waals interaction, symbols, Density functional theory, van der Waals force, 0210 nano-technology
Abstract

International audience; Van der Waals heterojunctions composed of graphene and transition metal dichalcogenides have gain much attention because of the possibility to control and tailor band structure, promising applications in two-dimensional optoelectronics and electronics. In this report, we characterized the van der Waals heterojunction MoSe$_2$/few-layer graphene with a high-quality interface using cutting-edge surface techniques scaling from atomic to microscopic range. These surface analyses gave us a complete picture of the atomic structure and electronic properties of the heterojunction. In particular, we found two important results: the commensurability between the MoSe$_2$ and few-layer graphene lattices and a band-gap opening in the few-layer graphene. The band gap is as large as 250 meV, and we ascribed it to an interface charge transfer that results in an electronic depletion in the few-layer graphene. This conclusion is well supported by electron spectroscopy data and density functional theory calculations. The commensurability between the MoSe$_2$ and graphene lattices as well as the band-gap opening clearly show that the interlayer interaction goes beyond the simple van der Waals interaction. Hence, stacking two-dimensional materials in van der Waals heterojunctions enables us to tailor the atomic and electronic properties of individual layers. It also permits the introduction of a band gap in few-layer graphene by interface charge transfer.

Published
2018
Full Text
View/download PDF

17. Beyond van der Waals Interaction: The Case of MoSe

Author

Minh Tuan, Dau, Maxime, Gay, Daniela, Di Felice, Céline, Vergnaud, Alain, Marty, Cyrille, Beigné, Gilles, Renaud, Olivier, Renault, Pierre, Mallet, Toai, Le Quang, Jean-Yves, Veuillen, Loïc, Huder, Vincent T, Renard, Claude, Chapelier, Giovanni, Zamborlini, Matteo, Jugovac, Vitaliy, Feyer, Yannick J, Dappe, Pascal, Pochet, and Matthieu, Jamet

Abstract

Van der Waals heterojunctions composed of graphene and transition metal dichalcogenides have gain much attention because of the possibility to control and tailor band structure, promising applications in two-dimensional optoelectronics and electronics. In this report, we characterized the van der Waals heterojunction MoSe

Published
2018

18. Non-local electrical spin injection and detection in germanium at room temperature

Author

Céline Vergnaud, Alain Marty, Michele Celebrano, Carlo Zucchetti, Jean-Philippe Attané, Julie Widiez, Henri Jaffrès, Matthieu Jamet, Alberto Ferrari, F. Rortais, Federico Bottegoni, Giovanni Isella, Franco Ciccacci, Jean-Marie George, Marco Finazzi, Lavinia Ghirardini, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Politecnico di Milano [Milan] (POLIMI), Unité mixte de physique CNRS/Thales (UMPhy CNRS/THALES), THALES-Centre National de la Recherche Scientifique (CNRS), ANR-13-BS10-0002,SiGeSPIN,Spintronique dans le silicium et le germanium(2013), and THALES [France]-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Physics and Astronomy (miscellaneous), Silicon, chemistry.chemical_element, FOS: Physical sciences, Germanium, 02 engineering and technology, 01 natural sciences, Electric charge, Signal, Condensed Matter::Materials Science, 0103 physical sciences, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, Spin (physics), Condensed Matter - Materials Science, business.industry, Materials Science (cond-mat.mtrl-sci), 021001 nanoscience & nanotechnology, 3. Good health, Tunnel magnetoresistance, Semiconductor, chemistry, Optoelectronics, Charge carrier, 0210 nano-technology, business
Abstract

Non-local carrier injection/detection schemes lie at the very foundation of information manipulation in integrated systems. This paradigm consists in controlling with an external signal the channel where charge carriers flow between a "source" and a well separated "drain". The next generation electronics may operate on the spin of carriers instead of their charge and germanium appears as the best hosting material to develop such a platform for its compatibility with mainstream silicon technology and the long electron spin lifetime at room temperature. Moreover, the energy proximity between the direct and indirect bandgaps allows for optical spin injection and detection within the telecommunication window. In this letter, we demonstrate injection of pure spin currents (\textit{i.e.} with no associated transport of electric charges) in germanium, combined with non-local spin detection blocks at room temperature. Spin injection is performed either electrically through a magnetic tunnel junction (MTJ) or optically, exploiting the ability of lithographed nanostructures to manipulate the distribution of circularly-polarized light in the semiconductor. Pure spin current detection is achieved using either a MTJ or the inverse spin-Hall effect (ISHE) across a platinum stripe. These results broaden the palette of tools available for the realization of opto-spintronic devices., Comment: 14 pages and 5 figures

Published
2017
Full Text
View/download PDF

19. Optical Orientation and Inverse Spin Hall Effect as Effective Tools to Investigate Spin-Dependent Diffusion

Author

Marco Finazzi 1, Federico Bottegoni 1, Carlo Zucchetti 1, Monica Bollani 2, Andrea Ballabio 1, Jacopo Frigerio 1, Fabien Rortais 3, 4, Céline Vergnaud 3, Alain Marty 3, Matthieu Jamet 3, Giovanni Isella 1, Franco Ciccacci 1, Politecnico di Milano [Milan] (POLIMI), SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Computer Networks and Communications, lcsh:TK7800-8360, 02 engineering and technology, optical orientation, spin current, inverse spin Hall effect, 01 natural sciences, Quantum spin Hall effect, 0103 physical sciences, Electrical and Electronic Engineering, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, ComputingMilieux_MISCELLANEOUS, Spin-½, Physics, Condensed matter physics, Spin polarization, business.industry, Scattering, lcsh:Electronics, Spin engineering, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 021001 nanoscience & nanotechnology, Semiconductor, Hardware and Architecture, Control and Systems Engineering, Signal Processing, Spinplasmonics, Spin Hall effect, Condensed Matter::Strongly Correlated Electrons, 0210 nano-technology, business
Abstract

In this work we address optical orientation, a process consisting in the excitation of spin polarized electrons across the gap of a semiconductor. We show that the combination of optical orientation with spin-dependent scattering leading to the inverse spin-Hall effect, i.e., to the conversion of a spin current into an electrical signal, represents a powerful tool to generate and detect spin currents in solids. We consider a few examples where these two phenomena together allow addressing the spin-dependent transport properties across homogeneous samples or metal/semiconductor Schottky junctions.

Published
2016
Full Text
View/download PDF

20. Transition from spin accumulation into interface states to spin injection in silicon and germanium conduction bands

Author

A. Jain, Matthieu Jamet, Jean-Christophe Le Breton, Jean-Philippe Attané, Juan-Carlos Rojas-Sánchez, Laurent Vila, Céline Vergnaud, Jean-Marie George, J. Peiro, Emmanuel Augendre, M. Cubukcu, Serge Gambarelli, Henri Jaffrès, Service de Physique des Matériaux et Microstructures (SP2M - UMR 9002), Institut Nanosciences et Cryogénie (INAC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Unité mixte de physique CNRS/Thales (UMPhy CNRS/THALES), THALES [France]-Centre National de la Recherche Scientifique (CNRS), Institut de Physique de Rennes (IPR), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Service de Chimie Inorganique et Biologique (SCIB - UMR E3), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-THALES, Université de Rennes 1 (UR1), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Spin pumping, Materials science, Spintronics, Spin polarization, Condensed matter physics, 02 engineering and technology, Magnetic semiconductor, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Electronic, Optical and Magnetic Materials, Condensed Matter::Materials Science, Spin wave, 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Spinplasmonics, Spin diffusion, Spin Hall effect, Condensed Matter::Strongly Correlated Electrons, 010306 general physics, 0210 nano-technology
Abstract

International audience; Electrical spin injection into semiconductors paves the way for exploring new phenomena in the area of spin physics and new generations of spintronic devices. However the exact role of interface states in the electrical spin injection mechanism from a magnetic tunnel junction into a semiconductor is still under debate. Here we demonstrate a clear transition from spin accumulation into interface states to spin injection in the conduction band of n-Si and n-Ge using a CoFeB/MgO tunnel contact. We observe spin signal amplification at low temperature due to spin accumulation into interface states followed by a clear transition towards spin injection in the conduction band from approximately 150 K up to room temperature. In this regime, the spin signal is reduced down to a value compatible with the standard spin diffusion model. More interestingly, in the case of germanium, we demonstrate a significant modulation of the spin signal by applying a back-gate voltage to the conduction channel. We also observe the inverse spin Hall effect in Ge by spin pumping from the CoFeB electrode. Both observations are consistent with spin accumulation in the Ge conduction band.

Published
2013
Full Text
View/download PDF

21. Electrical and thermal spin accumulation in germanium

Author

A. Jain, A. Barski, Matthieu Jamet, Vincent Baltz, Emmanuel Augendre, J. C. Le Breton, L. Louahadj, Pascale Bayle-Guillemaud, Henri Jaffrès, Céline Vergnaud, Clarisse Ducruet, J.-M. George, Eric Prestat, Jean-Philippe Attané, C. Portemont, Laurent Vila, Alain Marty, J. Peiro, Nanostructures et Magnétisme (NM), Service de Physique des Matériaux et Microstructures (SP2M - UMR 9002), Institut Nanosciences et Cryogénie (INAC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut Nanosciences et Cryogénie (INAC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Unité mixte de physique CNRS/Thales (UMPhy CNRS/THALES), THALES-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude des Matériaux par Microscopie Avancée (LEMMA ), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), CROCUS Technology, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), THALES [France]-Centre National de la Recherche Scientifique (CNRS), and Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG)

Subjects
Materials science, Physics and Astronomy (miscellaneous), FOS: Physical sciences, chemistry.chemical_element, Germanium, 02 engineering and technology, 01 natural sciences, Signal, Spin wave, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), 0103 physical sciences, Thermoelectric effect, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, Spin-½, Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics, Condensed matter physics, Materials Science (cond-mat.mtrl-sci), 021001 nanoscience & nanotechnology, Temperature gradient, chemistry, Ferromagnetism, Spin diffusion, Condensed Matter::Strongly Correlated Electrons, 0210 nano-technology
Abstract

In this letter, we first show electrical spin injection in the germanium conduction band at room temperature and modulate the spin signal by applying a gate voltage to the channel. The corresponding signal modulation agrees well with the predictions of spin diffusion models. Then by setting a temperature gradient between germanium and the ferromagnet, we create a thermal spin accumulation in germanium without any tunnel charge current. We show that temperature gradients yield larger spin accumulations than pure electrical spin injection but, due to competing microscopic effects, the thermal spin accumulation in germanium remains surprisingly almost unchanged under the application of a gate voltage to the channel., 7 pages, 3 figures

Published
2012
Full Text
View/download PDF

22. Study of injection and detection in silicon and germanium: From local measure of accumulation to nonlocal detection of pure spin current

Author

Rortais, Fabien, PHotonique, ELectronique et Ingénierie QuantiqueS (PHELIQS), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Université Grenoble Alpes, Matthieu Jamet, Céline Vergnaud, Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), UNIVERSITE GRENOBLE ALPES, STAR, ABES, and Rortais, Fabien

Subjects
[PHYS]Physics [physics], Silicon, Pure spin current, Germanium, Semiconducteur, Sillicium, Spintronics, Spin manipulation, [PHYS.COND.CM-MS] Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Pur courant de spin, [PHYS] Physics [physics], Manipulation de spin, Semiconductors, Semi-conducteur, Spin valve, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Silicium, Spintronique, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], [PHYS.COND] Physics [physics]/Condensed Matter [cond-mat], Vanne de spin
Abstract

Since the discovery of the giant magnetoresistance in 1988 by the group of Albert Fert (Nobel Prize in 2007), the field of spintronics has been growing very fast due to its potential applications in micro-electronics. For almost 20 years, it has been proposed to introduce the spin degree of freedom directly in the semiconducting materials. Spintronics aims at using not only the charge of carriers (electrons and holes) but also their intrinsic spin degree of freedom. In that case, spins might be manipulated with electric fields. By using both charge and spin, one might add new functionalities to traditional micro-electronic devices. Indeed, the first challenge of semiconductor spintronics is to create and detect a spin polarized carrier population in traditional semiconductors like Si and Ge to further manipulate them. For this purpose, we have used hybrid ferromagnetic metal/insulator/semiconductor devices which allow us to perform electrical spin injection and detection. The first part of this thesis deals with 3 terminal devices grown on different substrates and in which a single ferromagnetic electrode is used to inject and detect spin polarized electrons using the Hanle effect. A spin signal amplification is measured experimentally as compared to the value from the theoretical diffusive model, this raised a controversy concerning 3 terminal measurements. We demonstrate that localized defects in the tunnel barrier cannot be at the origin of the measured MR signal and spin signal amplification. Instead, we show that the presence of interface states is the origin of the spin signal amplification in all the substrates. By using a proper surface preparation and the MBE growth of the magnetic tunnel junctions, we reduce the density of interface states and show a significant modification of the spin signals. In a second part, we present the transition from 3 terminal measurements to lateral spin valves on semiconductors. In the last configuration by using two ferromagnetic electrodes, charge and spin currents are decoupled in order to avoid any spurious magnetoresistance artefacts. Using epitaxially grown magnetic tunnel junctions we can prove the spin injection in silicon and germanium. Especially, we are able to measure non local spin signals in germanium up to room temperature. Finally, we study the spin Hall effect in gallium arsenide and germanium substrates. For this propose we induce spin accumulation using the spin Hall effect (i.e spin-orbit coupling) and probe it using muon spectroscopy. We demonstrate, at low temperature the presence of spin accumulation by the coupling between nuclear spins and the electron spin accumulation., Depuis la découverte de la magnétorésistance (MR) géante en 1988 par le groupe d'Albert Fert (prix Nobel de physique en 2007), le domaine de l'électronique de spin a connu un essor sans précédent, justifié par toutes les applications qu'elle permet d'envisager en électronique. Depuis une vingtaine d'années, il est question d'utiliser le degré de liberté de spin directement dans les matériaux semi-conducteurs avec le gros avantage par rapport aux métaux de pouvoir manipuler électriquement le spin des porteurs. L'électronique de spin dans les matériaux semi-conducteurs utilise pour coder l'information non seulement la charge des porteurs (électrons et trous), mais aussi leur spin. En associant charge et spin, on ajoute de nouvelles fonctionnalités aux dispositifs de micro-électronique traditionnels. Le premier challenge consiste à contrôler l’injection et la détection d’une population de porteurs polarisés en spin dans les semiconducteurs traditionnels (Si, Ge). Pour cela, nous avons étudié des dispositifs hybrides de type MIS: Métal ferromagnétique/Isolant/Semi-conducteur qui nous permettent d'injecter et de détecter électriquement un courant de spin. La première partie de cette thèse concerne les dispositifs à 3 terminaux sur différents substrats qui utilisent une unique électrode ferromagnétique pour injecter et détecter par effet Hanle l’accumulation de spin dans les semi-conducteurs. Une amplification des signaux de spin extraits expérimentalement par rapport aux valeurs théoriques du modèle diffusif est à l’origine d’une controverse importante. Nous avons alors démontré que l’origine du signal de MR ou de l’amplification ne peut être expliquée par la présence de défauts dans la barrière tunnel. A l’inverse, nous prouvons la présence d’états d’interface qui peuvent expliquer l’amplification du signal de spin. De plus, la réduction de la densité d’états d’interface par une préparation de surface montre des changements significatifs comme la diminution du signal de spin. La deuxième partie de ces travaux concerne la transition vers les vannes de spin latérales sur semi-conducteurs. Dans ces dispositifs utilisant deux électrodes FM, le découplage entre l’injection et la détection de spin permet de s’affranchir des effets de magnétorésistance parasites car seul un pur courant de spin est détecté dans le semi-conducteur. Par une croissance d’une jonction tunnel ferromagnétique épitaxiée, nous avons démontré l’injection de spin dans des substrats de silicium et germanium sur isolant. En particulier nous observons un fort signal de spin jusqu’à température ambiante dans le germanium. Finalement, les prémices de la manipulation de spin par l’étude du couplage spin-orbite ont été étudiées dans les substrats d’arséniure de gallium et de germanium. En effet, nous avons induit par effet Hall de spin (une conséquence du couplage spin-orbite) une accumulation de spin qui a été sondée en utilisant la spectroscopie de muon. On démontre alors, à basse température, la présence de l’accumulation grâce au couplage entre les spins électroniques accumulés et les noyaux de l’arséniure de gallium.

Published
2016

Catalog

Books, media, physical & digital resources
See catalog results