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1. Ultrafast spectroscopy of coherent phonons across the pressure driven insulator to metal phase transition in V_{2}O_{3}

Author

Thomas Gauthier, Nicolas Godin, Gaël Privault, Roman Bertoni, Etienne Janod, Danylo Babich, Benoit Corraze, Julien Tranchant, and Laurent Cario

Subjects
Physics, QC1-999
Abstract

Nowadays, materials science is moving towards the understanding and control of materials in nonequilibrium states by making use of perturbative techniques to investigate their dynamical responses. From this perspective, the use of ultrashort light pulses seems to be a relevant approach as it can selectively address different degrees of freedom in solid-state systems and more particularly electrons. Such a method can help to decipher the physical phenomena arising from electronic correlations and complements a more conventional methodology where the phase diagrams of materials are investigated at thermodynamical equilibrium. Here, we combine femtosecond optical spectroscopy and a high-pressure setup to monitor the ultrafast out-of-equilibrium photo response of a V_{2}O_{3} thin film across the pressure driven insulator-to-metal transition. The experimental results demonstrate the possibility to use the spectroscopy of coherent phonons as a thermodynamical phase marker in V_{2}O_{3} thin films. In addition, the frequency behavior of the ultrafast coherent phonon mode (A_{1g} character) seems to reflect the manifestation of a strong coupling between the lattice and electronic degrees of freedom near first-order transition lines with a pronounced drop in frequency around the critical pressure.

Published
2024
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3. Design of metastable oxychalcogenide phases by topochemical (de)intercalation of sulfur in La2O2S2

Author

Shunsuke Sasaki, Maria Teresa Caldes, Catherine Guillot-Deudon, Isabelle Braems, Gwladys Steciuk, Lukáš Palatinus, Eric Gautron, Gilles Frapper, Etienne Janod, Benoît Corraze, Stéphane Jobic, and Laurent Cario

Subjects
Science
Abstract

Great progress has been made in topochemistry of mobile oxygen anions, but metastable compounds have not yet been achieved by deintercalation of sulfur anions. Here, the authors prepare metastable oxychalcogenide phases by taking advantage of redox-reactive sulfur dimers embedded in a layered oxysulfide.

Published
2021
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4. Direct experimental observation of the molecular J eff = 3/2 ground state in the lacunar spinel GaTa4Se8

Author

Min Yong Jeong, Seo Hyoung Chang, Beom Hyun Kim, Jae-Hoon Sim, Ayman Said, Diego Casa, Thomas Gog, Etienne Janod, Laurent Cario, Seiji Yunoki, Myung Joon Han, and Jungho Kim

Subjects
Science
Abstract

The strong interaction between electron spin and orbital degrees of freedom in 5d oxides can lead to exotic electronic ground states. Here the authors use resonant inelastic X-ray scattering to demonstrate that the theoretically proposed J eff = 3/2 state is realised in GaTa4Se8.

Published
2017
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8. Solvothermal and mechanochemical intercalation of Cu into La2O2S2 enabled by the redox reactivity of (S2)2− pairs

Author

Catherine Guillot-Deudon, Gwladys Steciuk, Etienne Janod, Isabelle Braems, Laurent Cario, Stéphane Jobic, Benoit Corraze, Shunsuke Sasaki, Maria Teresa Caldes, Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), J. Heyrovský Institute of Physical Chemistry of the ASCR, and Czech Academy of Sciences [Prague] (CAS)

Subjects
Materials science, Intercalation (chemistry), 02 engineering and technology, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Redox, 0104 chemical sciences, Inorganic Chemistry, Metal, visual_art, Polymer chemistry, visual_art.visual_art_medium, Reactivity (chemistry), 0210 nano-technology, Ball mill
Abstract

International audience; Intercalation of Cu into layered polychalcogenide La2O2S2 was demonstrated to be viable both in solvothermal condition at 200 °C and mechanical ball milling at ambient temperature. This result evidences the soft-chemical nature of metal intercalation into layered polychalcogenides driven by redox reactivity of anionanion bonds.

Published
2021
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9. Prediction of a New Layered Polymorph of FeS2 with Fe3+S2–(S22–)1/2 Structure

Author

Gilles Frapper, Laurent Cario, Shunsuke Sasaki, Frédéric Guégan, Isabelle Braems, Busheng Wang, and Stéphane Jobic

Subjects
Materials science, 010304 chemical physics, Structure (category theory), Crystal structure, 010402 general chemistry, 01 natural sciences, 0104 chemical sciences, Crystal structure prediction, Crystallography, Metastability, 0103 physical sciences, General Materials Science, Physical and Theoretical Chemistry, Iron disulfide
Abstract

The never-elucidated crystal structure of metastable iron disulfide FeS2 resulting from the full deintercalation of Li in Li2FeS2 has been cracked thanks to crystal structure prediction searches based on an evolutionary algorithm combined with first-principles calculations accounting for experimental observations. Besides the newly layered C2/m polymorph of iron disulfide, two-dimensional dynamically stable FeS2 phases are proposed that contain sulfides and/or persulfide S2 motifs.

Published
2020
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10. Artificial Electro-Optical Neuron Integrating Hot Electrons in a Mott Insulator

Author

Danylo Babich, Laurent Cario, Benoit Corraze, Maciej Lorenc, Julien Tranchant, Roman Bertoni, Marco Cammarata, Hervé Cailleau, Etienne Janod, Institut des Matériaux Jean Rouxel (IMN), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Nantes université - UFR des Sciences et des Techniques (Nantes univ - UFR ST), Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - Ecole Polytechnique de l'Université de Nantes (Nantes Univ - EPUN), Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ), Institut de Physique de Rennes (IPR), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), University of Nantes for financial support in the framework of the IM-LED LIA (CNRS)., and ANR-16-CE30-0018,ELASTICA,Cooperativité Elastique Photo-Induite dans des Matériaux Bistables avec Changement de Volume(2016)

Subjects
[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], General Physics and Astronomy, PACS: 07.05.Mh, [SPI.TRON]Engineering Sciences [physics]/Electronics
Abstract

International audience; Mott insulators are a class of strongly correlated materials with emergent properties important for modern electronics applications, such as artificial neural networks. Under an electric field, these compounds undergo a resistive switching that may be used to build up artificial neurons. However, the mechanism of this resistive switching is still under debate and may depend on the Mott material involved. Some works suggest an electronic avalanche phenomenon, while others propose an electrothermal scenario. As electric pulses produce both Joule heating and hot carriers, disentangling their respective roles requires the use of another external stimulus. Here, an ultrashort light pulse is used to tune the number of photogenerated carriers and the energy provided to the system. In these pump-pump-probe experiments, a crystal of the Mott insulator GaTa4Se8 is simultaneously excited by electric and laser pulses while an electric probe monitors its conductivity. The study shows that the resistive switching is affected by the number of generated photocarriers rather than by the accumulation of energy deposited by the femtosecond laser. It supports therefore a mechanism driven by generation of hot carriers. Finally, our work opens the possibility to build up an artificial electro-optical "Mott" neuron tuned by a femtosecond laser pulse.

Published
2022
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12. Contributors

Author

I.N. Antonov, A.I. Belov, C. Bonafos, S. Brivio, Laurent Cario, M. Carrada, Brigitte Caussat, Georgios Ch. Sirakoulis, Dennis Valbjørn Christensen, Elena Cianci, Benoit Corraze, V.A. Demin, P. Dimitrakis, A.V. Emelyanov, Manuel Escudero, Vincenzo Esposito, D.O. Filatov, Georgios Giannopoulos, O.N. Gorshkov, F. Gourbilleau, E.G. Gryaznov, D.V. Guseinov, Michael Hoffmann, Etienne Janod, Andreas Kaidatzis, L. Khomenkhova, D.S. Korolev, M.N. Koryazhkina, Yang Li, Qi Liu, Benjamin Max, A.N. Mikhaylov, Thomas Mikolajick, Halid Mulaosmanovic, Dimitris Niarchos, K.E. Nikiruy, P. Normand, E.V. Okulich, V.I. Okulich, D.A. Pavlov, Nini Pryds, Krishnaswamy Ramkumar, Antonio Rubio, V.V. Rylkov, Simone Sanna, S. Schamm-Chardon, Uwe Schroeder, M.E. Shenina, R.A. Shuisky, K.V. Sidorenko, A. Slaoui, Stefan Slesazeck, B. Spagnolo, Sabina Spiga, E. Talbot, Stefan Tappertzhofen, D.I. Tetelbaum, S.V. Tikhov, Julien Tranchant, Constantin Vahlas, E. Vianello, Ioannis Vourkas, and Xiaolong Zhao

Published
2022
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13. Photoinduced charge density wave phase in 1T-TaS2: growth and coarsening mechanisms

Author

Vincent Jacques, Steven L. Johnson, Laurent Cario, Claire Laulhé, Etienne Janod, Amélie Jarnac, and Sylvain Ravy

Subjects
Materials science, Condensed matter physics, Physics, Photoinduced phase transitions, Pump-probe X-ray diffraction, transition metal dichalcogenides, General Physics and Astronomy, Charge density wave compounds, Phase (matter), Condensed Matter::Superconductivity, Condensed Matter::Strongly Correlated Electrons, ddc:530, topological defects, Charge density wave
Abstract

Recent experiments have shown that the high-temperature incommensurate (I) charge density wave (CDW) phase of 1T-TaS2 can be photoinduced from the lower-temperature, nearly commensurate CDW state. In a first step, several independent regions exhibiting I-CDW phase modulations nucleate and grow. After coalescence, these regions form a multidomain I-CDW phase that undergoes coarsening dynamics, i.e. a progressive increase of the domain size or I-CDW correlation length. Using time-resolved X-ray diffraction, we show that the wave vector of the photoinduced I-CDW phase is shorter than in the I-CDW phase at equilibrium, and progressively increases towards its equilibrium value as the correlation length increases. We interpret this behaviour as a consequence of a self-doping of the photoinduced I-CDW, following the presence of trapped electrons in the vicinity of CDW dislocation sites. Putting together results of the present and past experiments, we develop a scenario in which the I-CDW dislocations are created during the coalescence of the I-CDW phase regions., Plusieurs expériences récentes ont montré que les impulsions laser dans les domaines optique ou proche infrarouge permettent de déclencher des transitions entre états à onde de densité de charge (ODC) dans 1T-TaS2. Nous nous intéressons ici à la transition entre l’état à ODC presque commensurable (NC) et l’état à ODC incommensurable (I), habituellement observé au-dessus de 350 K. Lors de cette transition, plusieurs régions présentant les modulations de l’état I se forment et se développent. Lorsque la coalescence a lieu, ces régions se muent en domaines de la phase I photoinduite de 1T-TaS2, caractérisés chacun par un phasage particulier de l’ODC I. La phase I ainsi fragmentée en domaines subit alors une dynamique de mûrissement, c’est-à-dire une augmentation progressive de la taille de domaine ou encore de la longueur de corrélation de l’ODC I. En utilisant la diffraction des rayons X résolue en temps, nous montrons que le vecteur d’onde de l’ODC I photoinduite est plus court que dans l’ODC I observée à l’équilibre thermodynamique. Celui-ci s’allonge progressivement vers sa valeur d’équilibre, en même temps que la longueur de corrélation de l’ODC I augmente. Nous attribuons ce comportement à un autodopage de l’ODC I photoinduite, dû à la présence d’électrons piégés au voisinage de dislocations de l’ODC I. En réalisant une synthèse des résultats des différentes expériences menées jusqu’à présent, nous développons un scénario dans lequel les dislocations de l’ODC I sont créées au moment de la coalescence., Comptes Rendus. Physique, 22 (S 2), ISSN:1631-0705, ISSN:1878-1535

Published
2021

14. Solvothermal and mechanochemical intercalation of Cu into La

Author

Shunsuke, Sasaki, Gwladys, Steciuk, Catherine, Guillot-Deudon, Maria Teresa, Caldes, Isabelle, Braems, Etienne, Janod, Benoît, Corraze, Stéphane, Jobic, and Laurent, Cario

Abstract

Intercalation of Cu into layered polychalcogenide La

Published
2021

16. Design of metastable oxychalcogenide phases by topochemical (de)intercalation of sulfur in La

Author

Shunsuke, Sasaki, Maria Teresa, Caldes, Catherine, Guillot-Deudon, Isabelle, Braems, Gwladys, Steciuk, Lukáš, Palatinus, Eric, Gautron, Gilles, Frapper, Etienne, Janod, Benoît, Corraze, Stéphane, Jobic, and Laurent, Cario

Subjects
Chemical synthesis, Solid-state chemistry, Article, Theoretical chemistry
Abstract

Designing and synthesising new metastable compounds is a major challenge of today’s material science. While exploration of metastable oxides has seen decades-long advancement thanks to the topochemical deintercalation of oxygen as recently spotlighted with the discovery of nickelate superconductor, such unique synthetic pathway has not yet been found for chalcogenide compounds. Here we combine an original soft chemistry approach, structure prediction calculations and advanced electron microscopy techniques to demonstrate the topochemical deintercalation/reintercalation of sulfur in a layered oxychalcogenide leading to the design of novel metastable phases. We demonstrate that La2O2S2 may react with monovalent metals to produce sulfur-deintercalated metastable phases La2O2S1.5 and oA-La2O2S whose lamellar structures were predicted thanks to an evolutionary structure-prediction algorithm. This study paves the way to unexplored topochemistry of mobile chalcogen anions., Great progress has been made in topochemistry of mobile oxygen anions, but metastable compounds have not yet been achieved by deintercalation of sulfur anions. Here, the authors prepare metastable oxychalcogenide phases by taking advantage of redox-reactive sulfur dimers embedded in a layered oxysulfide.

Published
2020

17. Misfit Layer Compounds: A Platform for Heavily Doped 2D Transition Metal Dichalcogenides

Author

Alexandra Palacio-Morales, Ondrej Šofranko, Marco Campetella, Cesare Tresca, Pascal David, Claude Monney, Imad Arfaoui, Laurent Cario, Shunsuke Sasaki, Christophe Brun, Tristan Cren, Geoffroy Kremer, Matteo Calandra, Raphaël T. Leriche, François Debontridder, Thomas Jaouen, Tomas Samuely, Sorbonne Université (SU), Institut des Nanosciences de Paris (INSP), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Saclay, Laboratoire de Physique des Solides (LPS), Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut des Matériaux Jean Rouxel (IMN), Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS), De la Molécule aux Nanos-objets : Réactivité, Interactions et Spectroscopies (MONARIS), P.J. Safarik University, Slovak Academy of Sciences (SAS), University of Fribourg, Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), University of Trento [Trento], IIT Graphene Labs, Istituto Italiano di Tecnologia (IIT), Spectroscopie des nouveaux états quantiques (INSP-E2), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), Centre of Low Temperature Physics IEP SAS (CLTP), Slovak Academy of Science [Bratislava] (SAS), ANR. Grant Numbers: ANR 15‐CE30‐0026‐02, ANR‐19‐CE24‐0028, ANR-15-CE30-0026,SUPERSTRIPES,Etats critiques de supraconducteurs confinés : de phénomènes mésoscopiques à une compréhension microscopique(2015), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Nantes université - UFR des Sciences et des Techniques (Nantes univ - UFR ST), Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - Ecole Polytechnique de l'Université de Nantes (Nantes Univ - EPUN), Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ), Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université de Fribourg = University of Fribourg (UNIFR), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), and ANR-19-CE24-0028,ACCEPT,AnharmoniC and exChangE interactions in Phonon specTra(2019)

Subjects
Charge density waves, Misfit compounds, Materials science, Photoemission spectroscopy, highly doped materials, misfit compounds, single layer materials, transition metal dichalcogenides, 02 engineering and technology, Electron, 010402 general chemistry, 01 natural sciences, Transition metal dichalcogenides, law.invention, Biomaterials, Condensed Matter::Materials Science, Highly doped materials, law, Condensed Matter::Superconductivity, Atom, Electrochemistry, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], [PHYS.COND.CM-MSQHE]Physics [physics]/Condensed Matter [cond-mat]/Mesoscopic Systems and Quantum Hall Effect [cond-mat.mes-hall], ComputingMilieux_MISCELLANEOUS, Single layer materials, Condensed matter physics, Doping, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 0104 chemical sciences, Electronic, Optical and Magnetic Materials, Coherence length, [PHYS.COND.CM-S]Physics [physics]/Condensed Matter [cond-mat]/Superconductivity [cond-mat.supr-con], Quasiparticle, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Condensed Matter::Strongly Correlated Electrons, Scanning tunneling microscope, [PHYS.COND.CM-SCE]Physics [physics]/Condensed Matter [cond-mat]/Strongly Correlated Electrons [cond-mat.str-el], 0210 nano-technology, Charge density wave
Abstract

International audience; Transition metal dichalcogenides (TMDs) display a rich variety of instabilities such as spin and charge orders, Ising superconductivity, and topological properties. Their physical properties can be controlled by doping in electric double‐layer field‐effect transistors (FET). However, for the case of single layer NbSe2, FET doping is limited to ≈1 × 1014 cm−2, while a somewhat larger charge injection can be obtained via deposition of K atoms. Here, by performing angle‐resolved photoemission spectroscopy, scanning tunneling microscopy, quasiparticle interference measurements, and first‐principles calculations it is shown that a misfit compound formed by sandwiching NbSe2 and LaSe layers behaves as a NbSe2 single layer with a rigid doping of 0.55–0.6 electrons per Nb atom or ≈6 × 1014 cm−2. Due to this huge doping, the 3 × 3 charge density wave is replaced by a 2 × 2 order with very short coherence length. As a tremendous number of different misfit compounds can be obtained by sandwiching TMDs layers with rock salt or other layers, this work paves the way to the exploration of heavily doped 2D TMDs over an unprecedented wide range of doping.

Published
2020
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18. Prediction of a New Layered Polymorph of FeS

Author

Busheng, Wang, Isabelle, Braems, Shunsuke, Sasaki, Frédéric, Guégan, Laurent, Cario, Stéphane, Jobic, and Gilles, Frapper

Abstract

The never-elucidated crystal structure of metastable iron disulfide FeS

Published
2020

19. Unusually long carrier lifetime in a Mott insulator revealed by time-resolved Photoemission Electron Microscopy

Author

Keiki Fukumoto, Danylo Babich, Benoit Corraze, Hervé Cailleau, Maciej Lorenc, Etienne Janod, S-Y Koshihara, Laurent Cario, Julien Tranchant, Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), KEK (High energy accelerator research organization), Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Tokyo Institute of Technology [Tokyo] (TITECH), Université de Nantes (UN)-Université de Nantes (UN)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, OCIS codes: 320, Insulator (electricity), 02 engineering and technology, Electron, 01 natural sciences, law.invention, law, Electric field, 0103 physical sciences, 010306 general physics, ComputingMilieux_MISCELLANEOUS, Condensed Matter::Quantum Gases, Condensed matter physics, Mott insulator, Carrier lifetime, 021001 nanoscience & nanotechnology, Photoemission electron microscopy, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Condensed Matter::Strongly Correlated Electrons, Electron microscope, [PHYS.COND.CM-SCE]Physics [physics]/Condensed Matter [cond-mat]/Strongly Correlated Electrons [cond-mat.str-el], 0210 nano-technology
Abstract

International audience; Mott insulators display puzzling insulator to metal transitions under electric field. We study here the Mott insulator GaV4S8 using time-resolved Photoemission Electron Microcopy and reveal unusually long carrier lifetimes, supporting the mechanism of electronic avalanche.

Published
2020

20. Competition between V2O3 phases deposited by one-step reactive sputtering process on polycrystalline conducting electrode

Author

Regina Dittmann, Laurent Cario, Etienne Janod, Madec Querré, J. A. J. Rupp, Rainer Waser, Andreas Kindsmüller, Julien Tranchant, B. Corraze, Marie-Paule Besland, Dirk J. Wouters, Rheinisch-Westfälische Technische Hochschule Aachen (RWTH), JARA-FIT, Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), and Res Ctr Julich GmbH

Subjects
Materials science, Scanning electron microscope, Analytical chemistry, Corundum, 02 engineering and technology, engineering.material, Reactive Sputtering, Bixbyite, 01 natural sciences, Vanadium Oxide, X-ray photoelectron spectroscopy, Sputtering, V 2 O 3, 0103 physical sciences, Materials Chemistry, Thin film, ComputingMilieux_MISCELLANEOUS, 010302 applied physics, Metals and Alloys, Vanadium Sesquioxide, Surfaces and Interfaces, 021001 nanoscience & nanotechnology, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Amorphous solid, Electrode, engineering, ddc:660, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Crystallite, [PHYS.COND.CM-SCE]Physics [physics]/Condensed Matter [cond-mat]/Strongly Correlated Electrons [cond-mat.str-el], 0210 nano-technology
Abstract

International audience; This comprehensive work investigates a technologically appealing synthesis of V 2 O 3 oxide thin films for electronic applications by the use of direct reactive sputtering with a heavily diluted gas mixture on a conducting platinum electrode. Morphological characterization was performed by Scanning Electron Microscopy, Atomic Force Microscopy , X-Ray Diffraction and X-Ray Reflectometry. Vanadium valence states were investigated by X-Ray Photoelectron Spectroscopy and crystalline phases were checked by X-Ray Grazing Incidence measurements. Low temperature electrical transport characteristics were determined by 2-point probe measurements. Only amorphous V 2 O 3 was found to exist in a mixed-valence phase in the 2 investigated parameter range. Deposition temperatures between 400 °C and 550 °C enable formation of mixtures between crystallographic phases of corundum-and bixbyite-type V 2 O polymorphs. Depending on temperature and sputtering power, morphology and stoichiometry can be tuned to generate four distinct type of electrical transport characteristics. Most promising electrical properties of corundum V 2 O 3 with a resistance ratio of up to four orders of magnitude (during the low temperature insulator-to-metal transition) have been obtained for a moderate sputtering power of 50 W (on a 1" target) at a deposition temperature of 600 °C. Reactive sputtering thus enables direct control of structural and electrical parameters for polycrystalline V 2 O 3 thin film phases on a conducting substrate.

Published
2020
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21. Periodic Surface Modulation of (LaSe) 1.14 (NbSe 2 ) Observed by Scanning Tunneling Microscopy

Author

A. P. Morales, Tomas Samuely, Laurent Cario, Pavol Szabó, Tristan Cren, Shunsuke Sasaki, Ondrej Šofranko, Peter Samuely, R. Leriche, P.J. Safarik University, Institut des Nanosciences de Paris (INSP), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), and Université de Nantes (UN)-Université de Nantes (UN)

Subjects
Materials science, FOS: Physical sciences, General Physics and Astronomy, 02 engineering and technology, 01 natural sciences, Molecular physics, law.invention, Superconductivity (cond-mat.supr-con), symbols.namesake, law, Lattice (order), Condensed Matter::Superconductivity, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), 0103 physical sciences, ComputingMilieux_MISCELLANEOUS, 010302 applied physics, Condensed Matter - Mesoscale and Nanoscale Physics, Hexagonal crystal system, Condensed Matter - Superconductivity, 021001 nanoscience & nanotechnology, Fourier transform, symbols, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Scanning tunneling microscope, 0210 nano-technology, Charge density wave
Abstract

Fourier transformation of atomically resolved STM topography of $(LaSe)_{1.14}(NbSe_2)$ revealed a surface modulation along the hexagonal surface lattice of $NbSe_2$ layer, but with a two times larger period. We compare it to the modified charge density wave found on plain $NbSe_2$ under strain., Withdrawn due to data re-evaluation

Published
2020
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22. Unexplored reactivity of (Sn)2− oligomers with transition metals in low-temperature solid-state reactions

Author

Benoit Corraze, Sylvian Cadars, Elodie Grange, Shunsuke Sasaki, Catherine Guillot-Deudon, Maria Teresa Caldes, Stéphane Jobic, Mélanie Lesault, Laurent Cario, Etienne Janod, Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), Conditions Extrêmes et Matériaux : Haute Température et Irradiation (CEMHTI), and Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université d'Orléans (UO)

Subjects
Materials science, Solid-state, FOS: Physical sciences, chemistry.chemical_element, Electron, 010402 general chemistry, 01 natural sciences, Catalysis, Soft chemistry, Metal, Transition metal, Materials Chemistry, Reactivity (chemistry), ComputingMilieux_MISCELLANEOUS, Condensed Matter - Materials Science, 010405 organic chemistry, Metals and Alloys, Materials Science (cond-mat.mtrl-sci), General Chemistry, Antibonding molecular orbital, Sulfur, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Crystallography, chemistry, visual_art, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Ceramics and Composites, visual_art.visual_art_medium
Abstract

Chalcogenides (Q = S, Se, Te), one of the most important family of materials in solid-state chemistry, differ from oxides by their ability to form covalently-bonded (Qn)2- oligomers. Each chalcogen atom within such entity fulfills the octet rule by sharing electrons with other chalcogen atoms but some antibonding levels are vacant. This makes these oligomers particularly suited for redox reactions in solid state, namely towards elemental metals with a low redox potential that may be oxidized. We recently used this strategy to design, at low temperature and in an orientated manner, materials with 2D infinite layers through the topochemical insertion of copper into preformed precursors containing (S2)2- and/or (Se2)2- dimers (i.e. La2O2S2, Ba2F2S2 and LaSe2). Herein we extend the validity of the concept to the redox activity of (S2)2- and (S3)2- oligomers towards 3d transition metal elements (Cu, Ni, Fe) and highlight the strong relationship between the structures of the precursors, BaS2 and BaS3, and the products, BaCu2S2, BaCu4S3, BaNiS2 and BaFe2S3. Clearly, beyond the natural interest for the chemical reactivity of oligomers to generate compounds, this soft chemistry route may conduct to the rational conception of materials with a predicted crystal structure.

Published
2019
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23. Strain wave pathway to semiconductor-to-metal transition revealed by time-resolved X-ray powder diffraction

Author

Simon Ebner, Majed Chergui, Hervé Cailleau, Paul Beaud, Henrik T. Lemke, Eric Collet, Gerhard Ingold, Alexei Bosak, Andrej Babic, Dmitry Ozerov, S. Vetter, Laurent Cario, Roman Bertoni, Laurent Guérin, Pavle Juranić, Michael Wulff, Giulia F. Mancini, Vincent Esposito, T. Zmofing, Alexander Roland Oggenfuss, Aldo Mozzanica, Shin-ichi Ohkoshi, Yunpei Deng, Maciej Lorenc, Ivan Usov, Serhane Zerdane, Matteo Levantino, Akos Schreiber, Marco Cammarata, Roman Mankowsky, Elzbieta Trzop, Rolf Follath, P. Böhler, Céline Mariette, S. Redford, C. Svetina, Olivier Hernandez, Leonardo Sala, A. Volte, X. Dong, L. Patthey, Hiroko Tokoro, V. Ta Phuoc, B. Lépine, A. Keller, Etienne Janod, Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), The University of Tokyo (UTokyo), Université de Tsukuba = University of Tsukuba, SwissFEL, Paul Scherrer Institut, SLAC National Accelerator Laboratory (SLAC), Stanford University, Ecole Polytechnique Fédérale de Lausanne (EPFL), European Synchrotron Radiation Facility (ESRF), IM‐LED LIA, Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Nantes (UN)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), ANR-16-CE30-0018,ELASTICA,Cooperativité Elastique Photo-Induite dans des Matériaux Bistables avec Changement de Volume(2016), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)

Subjects
Diffraction, Phase transition, Materials science, Electronic properties and materials, Bistability, Science, FOS: Physical sciences, General Physics and Astronomy, Physics::Optics, Applied Physics (physics.app-ph), 02 engineering and technology, 01 natural sciences, General Biochemistry, Genetics and Molecular Biology, Article, Condensed Matter::Materials Science, 0103 physical sciences, Physics::Atomic and Molecular Clusters, [CHIM]Chemical Sciences, 010306 general physics, [PHYS]Physics [physics], Condensed Matter - Materials Science, Multidisciplinary, Condensed matter physics, Materials Science (cond-mat.mtrl-sci), Physics - Applied Physics, General Chemistry, Acoustic wave, 021001 nanoscience & nanotechnology, 3. Good health, Phase transitions and critical phenomena, Picosecond, Femtosecond, 0210 nano-technology, Ultrashort pulse, Powder diffraction
Abstract

Thanks to the remarkable developments of ultrafast science, one of today's challenges is to modify material state by controlling with a light pulse the coherent motions that connect two different phases. Here we show how strain waves, launched by electronic and structural precursor phenomena, determine a macroscopic transformation pathway for the semiconducting-to-metal transition with large volume change in bistable Ti$_3$O$_5$ nanocrystals. Femtosecond powder X-ray diffraction allowed us to quantify the structural deformations associated with the photoinduced phase transition on relevant time scales. We monitored the early intra-cell distortions around absorbing metal dimers, but also long range crystalline deformations dynamically governed by acoustic waves launched at the laser-exposed Ti$_3$O$_5$ surface. We rationalize these observations with a simplified elastic model, demonstrating that a macroscopic transformation occurs concomitantly with the propagating acoustic wavefront on the picosecond timescale, several decades earlier than the subsequent thermal processes governed by heat diffusion., 30 pages (including supplementary text), 5 main figures, 9 supplementary figures; corrected author list

Published
2020
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24. Cu2O@CuO core-shell nanoparticles as photocathode for p-type dye sensitized solar cell

Author

Martine Bujoli-Doeuff, Fabrice Odobel, Yoann Farré, Yann Pellegrin, Eric Gautron, Mohammed Boujtita, Tengfei Jiang, Stéphane Jobic, and Laurent Cario

Subjects
Materials science, Mechanical Engineering, Metals and Alloys, Nanoparticle, chemistry.chemical_element, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Photocathode, 0104 chemical sciences, Dielectric spectroscopy, Dye-sensitized solar cell, X-ray photoelectron spectroscopy, Chemical engineering, chemistry, Mechanics of Materials, Screen printing, Materials Chemistry, 0210 nano-technology, High-resolution transmission electron microscopy, Cobalt
Abstract

Cu2O@CuO core-shell nanoparticles were synthesized via a facile precipitation-thermal oxidation method consisting in the preparation of Cu2O nanoparticles in solution followed by a post-treatment at 300 °C, 350 °C or 400 °C in air. From HRTEM micrographs, it was evidenced that Cu2O particles were uniformly covered by a 5 nm thick CuO layer to form a core-shell structure. This shell may be viewed as a passivating layer that overcomes the natural chemical instability of Cu2O towards electrolytes for instance. The as-obtained Cu2O@CuO nanoparticles were characterized by X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy. Both techniques concluded to the p-type conductivity of the Cu2O@CuO hetero-structures. These nanoparticles were then deposited as a film on a FTO glass by screen printing and used after sintering as photocathodes for p-DSSCs. Photovoltaic activity was confirmed with DPP-NDI dye as sensitizer and tris(4,4′-ditert-butyl-2,2′-bipyridine)cobalt(III/II) as redox mediator.

Published
2018
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25. A Topochemical Approach to Synthesize Layered Materials Based on the Redox Reactivity of Anionic Chalcogen Dimers

Author

Laurent Cario, Benoit Corraze, Elodie Grange, Maria Teresa Caldes, Dalel Driss, Jean-Yves Mevellec, Shunsuke Sasaki, Etienne Janod, Sylvian Cadars, Stéphane Jobic, Catherine Guillot-Deudon, Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), Conditions Extrêmes et Matériaux : Haute Température et Irradiation (CEMHTI), and Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université d'Orléans (UO)

Subjects
Materials science, New materials, chemistry.chemical_element, General Medicine, 02 engineering and technology, General Chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Redox, Copper, Catalysis, 0104 chemical sciences, Chalcogen, Crystallography, Transition metal, chemistry, Oxidation state, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Reactivity (chemistry), 0210 nano-technology, ComputingMilieux_MISCELLANEOUS, Topology (chemistry)
Abstract

Layered transition metal compounds represent a major playground to explore unconventional electric or magnetic properties. In that framework, topochemical approaches that mostly preserve the topology of layered reactants have been intensively investigated to tune properties and/or design new materials. Topochemical reactions often involve the insertion or deinsertion of a chemical element accompanied by a change of oxidation state of the cations only. Conversely, cases where anions play the role of redox centers are very scarce. Here we show that the insertion of copper into two dimensional precursors containing chalcogen dimers (Q2 )2- (Q=S, Se) can produce layered materials with extended (CuQ) sheets. The reality of this topochemical reaction is demonstrated here for different pristine materials, namely La2 O2 S2 , Ba2 F2 S2 , and LaSe2 . Therefore, this work opens up a new synthetic strategy to design layered transition metal compounds from precursors containing polyanionic redox centers.

Published
2018
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26. First demonstration of 'Leaky Integrate and Fire' artificial neuron behavior on (V0.95Cr0.05)2O3 thin film

Author

Pablo Stoliar, Benoit Corraze, Coline Adda, Julien Tranchant, Etienne Janod, Marcelo J. Rozenberg, Laurent Cario, and Marie-Paule Besland

Subjects
Materials science, business.industry, Mott insulator, Brain behavior, Oxide, chemistry.chemical_element, 02 engineering and technology, Sputter deposition, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, chemistry.chemical_compound, chemistry, Electrode, Artificial neuron, Optoelectronics, General Materials Science, Thin film, 0210 nano-technology, business, Tin
Abstract

A great challenge in the field of neurocomputing is to mimic the brain behavior by implementing artificial synapses and neurons directly in hardware. This work shows that a Leaky Integrate and Fire (LIF) artificial neuron can be realized with a two-terminal device made of Mott insulator thin films. Polycrystalline thin films of the well-known Mott insulator oxide (V0.95Cr0.05)2O3 were deposited by magnetron sputtering and patterned with micron-scale TiN electrodes. These devices exhibit a volatile resistive switching and a remarkable LIF behavior under a train of pulses suggesting that LIF artificial neurons may be realized from (V0.95Cr0.05)2O3 thin films.

Published
2018
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27. Hot carriers generation and resistive switching induced by electric and light pulses in the Mott insulator GaTa4Se8 (Conference Presentation)

Author

Roman Bertoni, Marina Servol, Laurent Cario, Hervé Cailleau, Marco Cammarata, Benoit Corraze, Danylo Babich, Etienne Janod, Maciej Lorenc, Céline Mariette, and Julien Tranchant

Subjects
Materials science, business.industry, Mott insulator, Physics::Optics, Laser, law.invention, Pulse (physics), Crystal, Wavelength, law, Electric field, Femtosecond, Optoelectronics, Condensed Matter::Strongly Correlated Electrons, Strongly correlated material, business
Abstract

Mott insulators are a class of strongly correlated materials with emergent properties important for modern electronics applications. The key property for application is the Electric Mott insulator to metal Transitions (EMT) whose proposed mechanism is related to the creation of hot electrons by electric field triggering an electronic avalanche after a time delay. This model suggests that the direct creation of hot carriers thanks to a laser pulse should drastically affect the EMT. We have tested this idea by performing pump-pump-probe experiments on single crystals of the Mott insulator GaTa4Se8, whereby electric and laser pulses simultaneously excite the crystal while electric probe monitors its conductivity. Our results show that the concomitant application of femtosecond laser pulse reduced the time delay of EMT by a factor up to. Measurements performed with different laser wavelengths and fluences support moreover that the EMT is driven by a hot carriers generation mechanism.

Published
2020
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28. Structure of the water-splitting photocatalyst oxysulfide α-LaOInS

Author

Houria, Kabbour, Adlane, Sayede, Sébastien, Saitzek, Gauthier, Lefèvre, Laurent, Cario, Martine, Trentesaux, and Pascal, Roussel

Abstract

We unveil the structure and investigate the visible light water-splitting of the photocatalyst α-LaOInS

Published
2020

29. Control of stoichiometry and morphology in polycrystalline V2O3 thin films using oxygen buffers

Author

Dirk J. Wouters, J. A. J. Rupp, Laurent Cario, Etienne Janod, Julien Tranchant, Benoit Corraze, Rainer Waser, Marie-Paule Besland, Rheinisch-Westfälische Technische Hochschule Aachen (RWTH), Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), Forschungszentrum Jülich GmbH | Centre de recherche de Juliers, and Helmholtz-Gemeinschaft = Helmholtz Association

Subjects
Materials science, Scanning electron microscope, Analytical chemistry, chemistry.chemical_element, 02 engineering and technology, Oxygen, V2O3, Sputtering, ddc:670, General Materials Science, Thin film, ComputingMilieux_MISCELLANEOUS, 020502 materials, Mechanical Engineering, Non-blocking I/O, Vanadium Sesquioxide, Partial pressure, [CHIM.MATE]Chemical Sciences/Material chemistry, Stoichiometry, 0205 materials engineering, chemistry, Mechanics of Materials, Oxygen Buffer, Buffer Couple, Crystallite, [PHYS.COND.CM-SCE]Physics [physics]/Condensed Matter [cond-mat]/Strongly Correlated Electrons [cond-mat.str-el]
Abstract

In this work, we investigate the influence of low temperature reduction conditions (873 K) by different oxygen buffers on the off-stoichiometry of polycrystalline V2O3 thin films. Vanadium oxide thin films (thickness 300 nm and 100 nm) have been grown by reactive sputtering and have been annealed in a buffered atmosphere subsequently. Buffer couples were chosen throughout the stability range of V2−yO3 (y ≤ 0.03) by the use of different oxygen buffer combinations, namely Ni/NiO, Fe/Fe3O4, Cr/Cr2O3 and Mn/MnO. Thin films have been characterized by scanning electron microscopy, X-ray diffractometry and low temperature electrical transport measurements. Upon decreasing the oxygen partial pressure, the mean grain size of V2O3 decreases systematically from 45 ± 20 nm with a high porosity to 27 ± 10 nm without porosity. The most favourable reduction conditions have been identified for Fe- and Cr-based couples. Moreover, all thin films reduced by the four buffer couples exhibit high insulator-to-metal transition temperatures (110–155 K) close to the value of ideally stoichiometric V2−yO3 (y

Published
2020
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30. Structure of the water-splitting photocatalyst oxysulfide α-LaOInS2 and ab initio prediction of new polymorphs

Author

Laurent Cario, Pascal Roussel, Sébastien Saitzek, Martine Trentesaux, Houria Kabbour, Adlane Sayede, Gauthier Lefevre, Unité de Catalyse et Chimie du Solide - UMR 8181 (UCCS), Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), UCCS Équipe Couches Minces & Nanomatériaux, Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), ANR-16-IDEX-0004,ULNE,ULNE(2016), Centrale Lille Institut (CLIL)-Université d'Artois (UA)-Centrale Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Lille, Centrale Lille Institut (CLIL)-Université d'Artois (UA)-Centrale Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Lille-Centrale Lille Institut (CLIL)-Université d'Artois (UA)-Centrale Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Lille, Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), and Université de Nantes (UN)-Université de Nantes (UN)

Subjects
Materials science, Ab initio, chemistry.chemical_element, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Catalysis, Ion, symbols.namesake, Materials Chemistry, Fermi level, Metals and Alloys, General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, [CHIM.CATA]Chemical Sciences/Catalysis, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Crystallography, chemistry, Octahedron, Ceramics and Composites, symbols, Photocatalysis, Water splitting, 0210 nano-technology, Indium, Visible spectrum
Abstract

International audience; We unveil the structure and investigate the visible light watersplitting photocatalyst α-LaOInS2, the second polymorph in this composition. This remarkable oxysulfide exhibits rare mixed anion InS5O octahedra leading to both O-2p and S-3p hybridized with indium states in the vicinity of the Fermi level. Ab initio structure prediction shows the stability of such heteroleptic environments and points other hypothetical polymorphs.

Published
2020
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31. THz Driven Dynamics in Mott Insulator GaTa4Se8

Author

Benoit Corraze, Sarah Houver, Steven L. Johnson, Elsa Abreu, Laurent Cario, Etienne Janod, Danylo Babich, Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), Laboratoire Pierre Aigrain (LPA), 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), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Field (physics), Condensed matter physics, Mott insulator, Drop (liquid), [CHIM.MATE]Chemical Sciences/Material chemistry, 01 natural sciences, 010305 fluids & plasmas, Mott transition, Electrical resistivity and conductivity, Picosecond, Electric field, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0103 physical sciences, [PHYS.COND.CM-SCE]Physics [physics]/Condensed Matter [cond-mat]/Strongly Correlated Electrons [cond-mat.str-el], 010306 general physics, Excitation
Abstract

International audience; GaTa4Se8 is a Mott insulator known to exhibit an electric Mott transition, characterized by a drop in electrical resistivity, when an electric field larger than 1-10 kV/cm is applied for a few tens of microseconds using electrodes deposited on the sample. Here, we show that a resistivity drop can be induced in this material within less than a picosecond. These dynamics occur after excitation by a high field THz pump pulse and persist for a few picoseconds, well beyond the duration of the pump pulse.

Published
2019
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32. Unexplored reactivity of (S

Author

Shunsuke, Sasaki, Mélanie, Lesault, Elodie, Grange, Etienne, Janod, Benoît, Corraze, Sylvian, Cadars, Maria Teresa, Caldes, Catherine, Guillot-Deudon, Stéphane, Jobic, and Laurent, Cario

Abstract

We demonstrate here the low temperature topochemical insertion of transition elements (Fe, Ni, and Cu) in precursors containing pre-formed (Sn)2- (n = 2 and 3) oligomers. Indeed, this soft chemistry route opens the door to the easy, orientated synthesis of low dimensional transition metal compounds provided that the elemental metal can retrocede electron(s) to empty antibonding sulfur σ* levels.

Published
2019

33. Combined First-Principles Calculations and Experimental Study of the Phonon Modes in the Multiferroic Compound GeV4S8

Author

Laurent Cario, Vinh Ta Phuoc, Etienne Janod, Elena Cannuccia, Marie Bernadette Lepetit, Benoit Corraze, Benjamin Brière, Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Théorie de la Matière Condensée (NEEL - TMC), 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]), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Théorie de la Matière Condensée (TMC ), Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Condensed matter physics, Scattering, Phonon, 02 engineering and technology, Dielectric, 021001 nanoscience & nanotechnology, 01 natural sciences, Ferroelectricity, Instability, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Condensed Matter::Materials Science, symbols.namesake, General Energy, Phase (matter), 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], symbols, Multiferroics, Physical and Theoretical Chemistry, 010306 general physics, 0210 nano-technology, Raman spectroscopy
Abstract

International audience; The lattice dynamics of the GeV4S8 compound has been investigated using both density functional calculations and Raman/infrared (IR) measurements. While the accordance between the computed and the experimental data is very good in the low-temperature, ferroelectric phase (25K, Imm2), this is not the case for the high-temperature, paraelectric one within the F4̅3m group. Using group theory and first-principles calculations, we show that the IR/Raman phonon modes are, however, compatible with the I4̅m2 space group. Analysis of the different modes at the ferroelectric transition shows that simultaneous weakening/strengthening of two symmetry-related bonds within the V4S4 cluster is a direct consequence of the orbital-order instability driving the ferroelectric transition. The softening of modes associated with such distortions call for strong orbital occupation fluctuations above Tc. These fluctuations, associated with the discrepancy between the X-ray scattering F4̅3m group and the lattice dynamics I4̅m2 group, can be interpreted within a dynamical Jahn–Teller distortion model for the paraelectric phase.

Published
2017
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34. (Invited) Control of Resistive Switching in Mott Memories Based on TiN/AM4Q8/TiN MIM Devices

Author

Julien Tranchant, Benoit Corraze, Pierre-Emmanuel Julien Marc Gaillardon, Davide Sacchetto, Laurent Cario, Jaafar Ghanbaja, Jury Sandrini, Etienne Janod, Giovanni De Micheli, and Marie-Paule Besland

Subjects
Resistive touchscreen, Materials science, business.industry, Chalcogenide, Mott insulator, Electrical engineering, chemistry.chemical_element, Resistive random-access memory, chemistry.chemical_compound, Neuromorphic engineering, chemistry, Microelectronics, Optoelectronics, Tin, business, Random access
Abstract

The family of AM4Q8 chalcogenide Mott insulators gained attention in recent years for its application opportunities. Here, we explore and validate the resistive switching mechanism of thin-film of GaV4S8 sandwiched between TiN electrodes. The device is fabricated via processes and materials compatible with microelectronics standards and demonstrates a good control and endurance of the non-volatile transitions over a large range of resistance. The achieved multi-level property enables to envision application as Resistive Random Access Memories (RRAM) or neuromorphic applications. We also showed the important role of the current compliance in the control of the transitions.

Published
2017
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35. Metal–insulator transitions in (V1-xCrx)2O3 thin films deposited by reactive direct current magnetron co-sputtering

Author

Benoit Corraze, Maryline Guilloux-Viry, Stéphanie Députier, Etienne Janod, Valérie Bouquet, Marie-Paule Besland, Stéphane Cordier, Madec Querré, Julien Tranchant, Laurent Cario, Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Université de Nantes (UN)-Université de Nantes (UN)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Scanning electron microscope, Analytical chemistry, Vanadium, chemistry.chemical_element, 02 engineering and technology, 01 natural sciences, V2O3, Sputtering, Phase (matter), 0103 physical sciences, Materials Chemistry, [CHIM]Chemical Sciences, Thin film, Composite material, Phase diagram, 010302 applied physics, Mott insulator, Metals and Alloys, Surfaces and Interfaces, 021001 nanoscience & nanotechnology, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, chemistry, Cavity magnetron, 0210 nano-technology
Abstract

International audience; Vanadium oxides are promising candidates for application in memory devices based on the control of their various metal–insulator transitions. We report here on the thin films deposition of the strongly correlated system (V1-xCrx)2O3 over a wide range of composition 0 ≤ x ≤ 0.60 by reactive DC magnetron co-sputtering of pure V and Cr targets. Thin films were characterized by Scanning Electron Microscopy, Energy Dispersive X-ray spectroscopy, X-ray diffraction and transport measurements. These studies demonstrates the existence of compressive stress reaching 0.8 GPa in 200 nm thick films, whereas thicker 1 μm films exhibit lower internal stress. This compressive stress modifies significantly the phase diagram of the 200 nm films, shifting the critical chromium content triggering the bandwidth-controlled metal–insulator transition from x = 0.011 in unstressed films to more than 0.04. This work highlights the need for an accurate control of the Cr content and of the compressive stress to stabilize the Mott insulator phase in (V1-xCrx)2O3 thin films

Published
2016
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36. Modulation of Defects in Semiconductors by Facile and Controllable Reduction: The Case of p-type CuCrO2 Nanoparticles

Author

Laurent Cario, Romain Gautier, Xueyan Li, Martine Bujoli-Doeuff, Tengfei Jiang, Stéphane Jobic, Eric Gautron, Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), Bioinformatique génomique et moléculaire ((U 726)), and Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Paris Diderot - Paris 7 (UPD7)

Subjects
Chemistry, business.industry, Nanoparticle, Nanotechnology, 02 engineering and technology, engineering.material, Conductivity, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, Inorganic Chemistry, Reduction (complexity), Delafossite, Semiconductor, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], engineering, Charge carrier, Physical and Theoretical Chemistry, 0210 nano-technology, Absorption (electromagnetic radiation), business, Electrical conductor, ComputingMilieux_MISCELLANEOUS
Abstract

Optical and electrical characteristics of solid materials are well-known to be intimately related to the presence of intrinsic or extrinsic defects. Hence, the control of defects in semiconductors is of great importance to achieve specific properties, for example, transparency and conductivity. Herein, a facile and controllable reduction method for modulating the defects is proposed and used for the case of p-type delafossite CuCrO2 nanoparticles. The optical absorption in the infrared region of the CuCrO2 material can then be fine-tuned via the continuous reduction of nonstoichiometric Cu(II), naturally stabilized in small amounts. This reduction modifies the concentration of positive charge carriers in the material, and thus the conductive and reflective properties, as well as the flat band potential. Indeed, this controllable reduction methodology provides a novel strategy to modulate the (opto-) electronic characteristics of semiconductors.

Published
2016
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37. Preparation by electrophoretic deposition of molybdenum iodide cluster-based functional nanostructured photoelectrodes for solar cells

Author

Fabien Grasset, Noée Dumait, Tetsuo Uchikoshi, F. Delabrouille, Thi Kim Ngan Nguyen, Fabrice Odobel, Yann Pellegrin, P.-Y. Jouan, Laurent Cario, Stéphane Cordier, V. Guillon, Stéphane Jobic, Adèle Renaud, Mahfoudh Raïssi, Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Laboratory for Innovative Key Materials and Structures (LINK), SAINT-GOBAIN-National Institute of Materials Science-Centre National de la Recherche Scientifique (CNRS), National Institute for Materials Science (NIMS), Chimie Et Interdisciplinarité : Synthèse, Analyse, Modélisation (CEISAM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), EDF R&D (EDF R&D), EDF (EDF), Institut des Matériaux Jean Rouxel (IMN), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), Saint-GobainSaint-Gobain, Centre National de la Recherche ScientifiqueCentre National de la Recherche Scientifique, National Institute for Materials ScienceNational Institute for Materials Science, UMI3629 LINK, Laboratory for Innovative Key Materials and Structures, Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Saint-Gobain-National Institute of Materials Science-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Nantes (UN)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and Université de Nantes (UN)-Université de Nantes (UN)-Ecole Polytechnique de l'Université de Nantes (EPUN)

Subjects
Solar cells, Materials science, General Chemical Engineering, chemistry.chemical_element, 02 engineering and technology, 010402 general chemistry, 7. Clean energy, 01 natural sciences, law.invention, Electrophoretic deposition, law, Solar cell, Electrochemistry, Photoelectrodes, Thin film, ComputingMilieux_MISCELLANEOUS, Molybdenum, Non-blocking I/O, Photovoltaic system, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Metallic cluster, 0104 chemical sciences, chemistry, Chemical engineering, Electrode, 0210 nano-technology, Mesoporous material
Abstract

This work explores the potentiality of Mo6 clusters as new inorganic sensitizers with amphoteric properties for photoelectronic applications being non-toxic and stable. It reports on the design of photoelectrodes by electrophoretic deposition (EPD) of molybdenum octahedral metal cluster iodide (CMI) onto mesoporous TiO2 and NiO layers before being deposited on FTO (i. e. CMI@TSO@FTO, TSO = TiO2 or NiO). Indeed, the low-cost, low-waste and industrially scalable EPD method has allowed for the achievement of transparent, homogeneous orange/red [Mo6Ii8]4+ cluster core-based films, and appears suitable for the sensitization of TiO2- and NiO-based electrodes of n- and p-type solar cells inspired from dye-sensitized solar cells (DSSCs). First, the EPD process was optimized by the direct deposition of CMI onto an FTO substrate (CMI@FTO) leading to the realization of highly transparent colored films. Second, strongly colored CMI@TSO@FTO photoelectrodes were achieved and integrated into solar cell devices. Hence, compared to the classical soaking method, the EPD process significantly improves the quality (i.e., its homogeneity and absorption properties) of the photoelectrodes, leading consequently to much better photovoltaic performances.

Published
2019
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38. How a dc Electric Field Drives Mott Insulators Out of Equilibrium

Author

Alberto Camjayi, Stéphane Cordier, Laurent Cario, P. Diener, Marie-Paule Besland, Coline Adda, Benoit Corraze, Madec Querré, Marcelo J. Rozenberg, Maryline Guilloux-Viry, Etienne Janod, Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), Laboratoire de Chimie du solide et inorganique moléculaire (LCSIM), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR), Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), 16-CE30-0018, Agence Nationale de la Recherche, Région Pays de la Loire, pari scientifique Neuro-Mott, ANR-16-CE30-0018,ELASTICA,Cooperativité Elastique Photo-Induite dans des Matériaux Bistables avec Changement de Volume(2016), Université de Nantes (UN)-Université de Nantes (UN)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
INSULATOR, Ciencias Físicas, Electrical breakdown, General Physics and Astronomy, Insulator (electricity), 02 engineering and technology, 01 natural sciences, purl.org/becyt/ford/1 [https], Electric field, 0103 physical sciences, 010306 general physics, MOTT, ComputingMilieux_MISCELLANEOUS, Physics, Resistive touchscreen, OUT, Condensed matter physics, Mott insulator, purl.org/becyt/ford/1.3 [https], 021001 nanoscience & nanotechnology, EQUILIBRIUM, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Microscopic theory, 0210 nano-technology, Hot electron, CIENCIAS NATURALES Y EXACTAS, Física de los Materiales Condensados
Abstract

Out of equilibrium phenomena are a major issue of modern physics. In particular, correlated materials such as Mott insulators experience fascinating long-lived exotic states under a strong electric field. Yet, the origin of their destabilization by the electric field is not elucidated. Here we present a comprehensive study of the electrical response of canonical Mott insulators GaM4Q8 (M=V, Nb, Ta, Mo; Q=S, Se) in the context of a microscopic theory of electrical breakdown where in-gap states allow for a description in terms of a two-temperature model. Our results show how the nonlinearities and the resistive transition originate from a massive creation of hot electrons under an electric field. These results give new insights for the control of the long-lived states reached under an electric field in these systems which has recently open the way to new functionalities used in neuromorphic applications. Fil: Diener, P.. Universite de Nantes; Francia Fil: Janod, E.. Universite de Nantes; Francia Fil: Corraze, B.. Universite de Nantes; Francia Fil: Querré, M.. Universite de Rennes I. Institut Des Sciences Chimiques de Rennes.; Francia. Universite de Nantes; Francia Fil: Adda, C.. Universite de Nantes; Francia Fil: Guilloux Viry, M.. Universite de Rennes I. Institut Des Sciences Chimiques de Rennes.; Francia Fil: Cordier, S.. Universite de Rennes I. Institut Des Sciences Chimiques de Rennes.; Francia Fil: Camjayi, Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina Fil: Rozenberg, Marcelo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Université Paris Sud; Francia Fil: Besland, M. P.. Universite de Nantes; Francia Fil: Cario, L.. Universite de Nantes; Francia

Published
2018
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39. Mott Memory Devices Based on the Mott Insulator (V1-xCrx)2O3

Author

Marie-Paule Besland, Etienne Janod, Benoet Corraze, Laurent Cario, Julien Tranchant, and Madec Querré

Subjects
010302 applied physics, Materials science, business.industry, Chalcogenide, Mott insulator, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Mott transition, chemistry.chemical_compound, chemistry, Memory cell, 0103 physical sciences, Electrode, Optoelectronics, Microelectronics, Electric potential, Thin film, 0210 nano-technology, business
Abstract

The discovery of an electric Mott transition (EMT) in Mott insulators has paved the way for their use in a new type of non-volatile memories, the Mott memories. While most of the previous studies were dedicated to the memory potential of chalcogenide Mott insulators, we present here new results obtained on a memory cell device based on the canonical Mott insulator oxide (V0.95Cr0.05)2O3. Devices are compatible with most microelectronics standards and thin films demonstrate an excellent crystalline quality which ensures that the resistive switching is based on the EMT. Performances obtained on 100 nm thick layers with 330 nm electrodes are very competitive. Indeed, without filament forming step, features such as 3.5 V / 100 ns programming pulses, 48 µA writing current, 8 pJ writing energy or endurance of 5000 cycles demonstrate the strong potential of Mott memories. Besides we show that Cr-free 20 nm thick strained-V2O3 layers are promising as Mott memory active material.

Published
2018
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40. Ba2F2Fe1.5Se3: An Intergrowth Compound Containing Iron Selenide Layers

Author

Dalel Driss, Catherine Guillot-Deudon, Etienne Janod, Laurent Cario, Benoit Corraze, Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), and Université de Nantes (UN)-Université de Nantes (UN)

Subjects
Valence (chemistry), Nanotechnology, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Fluorite, 0104 chemical sciences, Inorganic Chemistry, chemistry.chemical_compound, Crystallography, chemistry, Octahedron, Electrical resistivity and conductivity, Selenide, visual_art, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], visual_art.visual_art_medium, Tetrahedron, Antiferromagnetism, Ceramic, Physical and Theoretical Chemistry, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS
Abstract

The iron selenide compound Ba2F2Fe(1.5)Se3 was synthesized by a high-temperature ceramic method. The single-crystal X-ray structure determination revealed a layered-like structure built on [Ba2F2](2+) layers of the fluorite type and iron selenide layers [Fe(1.5)Se3](2-). These [Fe1.5Se3](2-) layers contain iron in two valence states, namely, Fe(II+) and Fe(III+) located in octahedral and tetrahedral sites, respectively. Magnetic measurements are consistent with a high-spin state for Fe(II+) and an intermediate-spin state for Fe(III+). Moreover, susceptibility and resistivity measurements demonstrate that Ba2F2Fe(1.5)Se3 is an antiferromagnetic insulator.

Published
2016
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41. Coherent long-range magnetic bound states in a superconductor

Author

Dimitri Roditchev, Gerbold Menard, François Debontridder, Pascal Simon, Matthieu V. Leclerc, Sébastien Guissart, Christophe Brun, Etienne Janod, Tristan Cren, Laurent Cario, Vasily S. Stolyarov, Stéphane Pons, Institut des Nanosciences de Paris (INSP), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Spectroscopie des nouveaux états quantiques (INSP-E2), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique des Solides d'Orsay (LPS), Universirté d'Orsay, Laboratoire de Physique et d'Etude des Matériaux (UMR 8213) (LPEM), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Moscow Institute of Physics and Technology [Moscow] (MIPT), Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), and Université de Nantes (UN)-Université de Nantes (UN)

Subjects
Physics, Superconductivity, Range (particle radiation), Condensed matter physics, Niobium, General Physics and Astronomy, chemistry.chemical_element, [PHYS.COND.CM-S]Physics [physics]/Condensed Matter [cond-mat]/Superconductivity [cond-mat.supr-con], chemistry.chemical_compound, chemistry, Condensed Matter::Superconductivity, Selenide, Bound state, Physics::Atomic Physics, Atomic physics, ComputingMilieux_MISCELLANEOUS
Abstract

International audience; The quantum coupling of fully different degrees of freedom is a challenging path towards new functionalities for quantum electronics [1–3]. Here we show that the localized classical spin of a magnetic atom immersed in a superconductor with a two-dimensional electronic band structure gives rise to a long range coherent magnetic quantum state. We experimentally evidence coherent bound states with spatially oscillating particle-hole asymmetry extending tens of nanometers from individual iron atoms embedded in a 2H-NbSe 2 crystal. We theoretically elucidate how reduced dimensionality enhances the spatial extent of these bound states and describe their energy and spatial structure. These spatially extended magnetic states could be used as building blocks for coupling coherently distant magnetic atoms in new topological superconducting phases [4–11].

Published
2015
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43. Higgs-mode radiance and charge-density-wave order in 2H-NbSe2

Author

Lara Benfatto, Laurent Cario, Tommaso Cea, Maximilien Cazayous, Romain Grasset, Alain Sacuto, Yann Gallais, Marie-Aude Méasson, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institute IMDEA Materials [Madrid], Institute IMDEA Materials, IIT Graphene Labs, Istituto Italiano di Tecnologia (IIT), Istituto Sistemi Complessi [ROME] (ISC), Consiglio Nazionale delle Ricerche [Roma] (CNR), Cytokines, chimiokines et immunopathologie, Université Paris-Sud - Paris 11 (UP11)-Institut National de la Santé et de la Recherche Médicale (INSERM), Laboratoire Physique des Solides de Toulouse, Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), Univ Roma La Sapienza, Dept Phys, CNR ISC, I-00185 Rome, Italy, Magnétisme et Supraconductivité (MagSup ), 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]), ANR-10-LABX-0096,SEAM,Science and Engineering for Advanced Materials and devices(2010), ANR-11-BS04-0002,PRINCESS,Instrumentation et études novatrices sur les systèmes à électrons corrélés sous pression(2011), ANR-16-CE30-0014,SEO-HiggS2,Spectroscopie des Ordres Exotiques – le boson de Higgs dans les Supraconducteurs(2016), Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS), MagSup - Magnétisme et Supraconductivité, Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), ANR-11-LABX-086 - ANR-11-IDEX-05-02,LabEx SEAM,Science and Engineering for Advanced Materials and devices, and ANR-16-CE30-0014 ,SEO-HiggS2,Spectroscopie des Ordres Exotiques – le boson de Higgs dans les Supraconducteurs

Subjects
Phase transition, RAMAN-SCATTERING, Phonon, Degrees of freedom (physics and chemistry), FOS: Physical sciences, 02 engineering and technology, 01 natural sciences, Superconductivity (cond-mat.supr-con), Dichalcogenides, symbols.namesake, Condensed Matter - Strongly Correlated Electrons, SUPERCONDUCTORS, Condensed Matter::Superconductivity, 0103 physical sciences, COLLECTIVE MODES, SPECTROSCOPY, 010306 general physics, Superconductivity, Physics, Higgs bosons, Strongly Correlated Electrons (cond-mat.str-el), Condensed matter physics, Condensed Matter - Superconductivity, Order (ring theory), 021001 nanoscience & nanotechnology, symbols, Higgs boson, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 0210 nano-technology, Raman spectroscopy, Higgs-mode radiance, Charge density wave
Abstract

Despite being usually considered two competing phenomena, charge-density wave and superconductivity coexist in few systems, the most emblematic one being the transition-metal dichalcogenide $2H\ensuremath{-}{\mathrm{NbSe}}_{2}$. This unusual condition is responsible for specific Raman signatures across the two phase transitions in this compound. While the appearance of a soft phonon mode is a well-established fingerprint of the charge-density-wave order, the nature of the sharp subgap mode emerging below the superconducting temperature is still under debate. In this work we use external pressure as a knob to unveil the delicate interplay between the two orders, and consequently the nature of the superconducting mode. Thanks to an advanced extreme-conditions Raman technique, we are able to follow the pressure evolution and the simultaneous collapse of the two intertwined charge-density-wave and superconducting modes. The comparison with microscopic calculations in a model system supports the Higgs-type nature of the superconducting mode and suggests that charge-density wave and superconductivity in $2H\ensuremath{-}{\mathrm{NbSe}}_{2}$ involve mutual electronic degrees of freedom. These findings fill the knowledge gap on the electronic mechanisms at play in transition-metal dichalcogenides, a crucial step to fully exploit their properties in few-layer systems optimized for device applications.

Published
2018
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44. Non-volatile resistive switching in the Mott insulator (V1-xCrx)(2)O-3

Author

Stéphane Cordier, Maryline Guilloux-Viry, Stéphanie Députier, Marie-Paule Besland, Benoit Corraze, Laurent Cario, Etienne Janod, Valérie Bouquet, Julien Tranchant, Madec Querré, Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), SATT Ouest-Valorisation, CNRS, Region Pays de la Loire, Université de Nantes (UN)-Université de Nantes (UN)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, ReRAM, Mott transition, Chalcogenide, Insulator (electricity), 02 engineering and technology, 010402 general chemistry, 01 natural sciences, V2O3, chemistry.chemical_compound, [CHIM]Chemical Sciences, Resistive switching, Electrical and Electronic Engineering, Metal–insulator transition, ComputingMilieux_MISCELLANEOUS, Phase diagram, Condensed Matter::Quantum Gases, Mott insulators, Condensed matter physics, Mott insulator, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 0104 chemical sciences, Electronic, Optical and Magnetic Materials, Resistive random-access memory, Non-volatile memory, chemistry, Condensed Matter::Strongly Correlated Electrons, 0210 nano-technology
Abstract

The discovery of non-volatile resistive switching in Mott insulators related to an electric-field-induced insulator to metal transition (IMT) has paved the way for their use in a new type of non-volatile memories, the Mott memories. While most of the previous studies were dedicated to uncover the resistive switching mechanism and explore the memory potential of chalcogenide Mott insulators, we present here a comprehensive study of resistive switching in the canonical oxide Mott insulator (V1−xCrx)2O3. Our work demonstrates that this compound undergoes a non-volatile resistive switching under electric field. This resistive switching is induced by a Mott transition at the local scale which creates metallic domains closely related to existing phases of the temperature-pressure phase diagram of (V1−xCrx)2O3. Our work demonstrates also reversible resistive switching in (V1−xCrx)2O3 crystals and thin film devices. Preliminary performances obtained on 880 nm thick layers with 500 nm electrodes show the strong potential of Mott memories based on the Mott insulator (V1−xCrx)2O3.

Published
2018
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45. Traces of Charge Density Waves in NbS$_2$

Author

Pierre Rodière, Maxime Leroux, Laurent Cario, Alexei Bosak, Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), European Synchrotron Radiation Facility (ESRF), Magnétisme et Supraconductivité (MagSup ), Institut Néel (NEEL), and 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])

Subjects
Physics, Condensed matter physics, Strongly Correlated Electrons (cond-mat.str-el), Scattering, Superlattice, Charge density, FOS: Physical sciences, Bragg peak, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, [PHYS.COND.CM-S]Physics [physics]/Condensed Matter [cond-mat]/Superconductivity [cond-mat.supr-con], Condensed Matter - Strongly Correlated Electrons, Transition metal, Lattice (order), 0103 physical sciences, [PHYS.COND.CM-SCE]Physics [physics]/Condensed Matter [cond-mat]/Strongly Correlated Electrons [cond-mat.str-el], 010306 general physics, 0210 nano-technology, Charge density wave
Abstract

Among Transition Metal Dichalcogenides (TMD), NbS$_2$ is often considered as the archetypal compound that does not have a Charge Density Wave (CDW) in any of its polytypes. By comparison, close iso-electronic compounds such as NbSe$_2$, TaS$_2$ and TaSe$_2$ all have CDW in at least one polytype. Here, we report traces of CDW in the 2H polytype of NbS$_2$, using diffuse x-ray scattering measurements at 77\,K and room temperature. We observe 12 extremely weak satellite peaks located at $\pm$13$^\mathrm{o}$ 54' from $\vec{a}^*$ and $\vec{b}^*$ around each Bragg peaks in the $(h,k,0)$ plane. These satellite peaks are commensurate with the lattice via $3\vec{q}-\vec{q}\,'=\vec{a}^*$, where $\vec{q}\,'$ is the 120$^{\circ}$ rotation of $\vec{q}$, and define two chiral $\sqrt{13}\,a\times\sqrt{13}\,a$ superlattices in real space. These commensurate wavevectors and tilt angle are identical to those of the CDW observed in the 1T polytype of TaS$_2$ and TaSe$_2$. To understand this similarity and the faintness of the peaks, we discuss possible sources of local 1T polytype environment in bulk 2H-NbS$_2$ crystals.

Published
2018
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46. X-ray study of femtosecond structural dynamics in the 2D charge density wave compound 1T-TaS2

Author

Benoit Corraze, Sylvain Ravy, T. Huber, Claire Laulhé, Andrés Ferrer, Gabriel Lantz, S. Grübel, A. Lübcke, Steven L. Johnson, Paul Beaud, S. Boulfaat, Etienne Janod, S. O. Mariager, Laurent Cario, Gert L. Ingold, Jeremy A. Johnson, Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique des Solides (LPS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Laboratoire de Chimie Physique - Matière et Rayonnement (LCPMR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Universidad Nacional de Córdoba [Argentina], and Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Diffraction, Phase transition, Materials science, Photon, Condensed matter physics, Phase (waves), 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Molecular physics, Electronic, Optical and Magnetic Materials, Amplitude, 0103 physical sciences, Femtosecond, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Electrical and Electronic Engineering, 010306 general physics, 0210 nano-technology, Charge density wave, ComputingMilieux_MISCELLANEOUS, Excitation
Abstract

1T-TaS2 is a 2D metallic compound which undergoes a series of electronically driven phase transitions toward charge density wave and Mott phases. Its intricate electron–phonon interactions and electron–electron correlations have been promising peculiar out-of-equilibrium dynamics. In this paper, we provide the first direct information on the atomic structure response to an ultra-fast infrared laser pulse in the commensurate phase of 1T-TaS2, by using femtosecond time-resolved X-ray diffraction. We show that ultra-fast excitation with near-infrared photons drives a displacive excitation of the amplitude mode of the commensurate charge density wave. About 3 ps after laser excitation, the system reaches a new, photo-induced state that is maintained for at least 10 ps. We give evidence that this long-lived state exhibits the same structural modulation as in the thermodynamically stable commensurate phase, with a large correlation length. Only the average amplitude of the modulation is found to decrease. We propose that the long-lived state is formed from the commensurate phase by reducing the modulation amplitude on few superlattice nodes. The underlying mechanism proposed is the annihilation of self-trapped polarons.

Published
2015
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47. The first dye-sensitized solar cell with p-type LaOCuS nanoparticles as a photocathode

Author

Laurent Cario, Errol Blart, Mohammed Boujtita, Adèle Renaud, Fabrice Odobel, Yann Pellegrin, Stéphane Jobic, Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), Chimie Et Interdisciplinarité : Synthèse, Analyse, Modélisation (CEISAM), and Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)

Subjects
Materials science, business.industry, General Chemical Engineering, Non-blocking I/O, Wide-bandgap semiconductor, Nanoparticle, Nanotechnology, General Chemistry, 7. Clean energy, Transparent electronics, Photocathode, Dye-sensitized solar cell, Semiconductor, [CHIM]Chemical Sciences, Optoelectronics, business
Abstract

Layered LaOCuS oxysulfide is a well-known wide band gap p-type semiconductor that has attracted strong interests for transparent electronics. We report here that nanoparticles of this material can also be used as a substitute for the widely used NiO compound to fabricate photocathodes for p-type dye sensitized solar cells.

Published
2015
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48. Domain-size effects on the dynamics of a charge density wave in 1T−TaS2

Author

Michael Porer, K. Tasca, A. Ciavardini, Gabriel Lantz, M. Kubli, J. Rittmann, Paul Beaud, Laurent Cario, Claire Laulhé, Steven L. Johnson, Matteo Savoini, S. Ravy, Vincent Esposito, and Elsa Abreu

Subjects
Physics, Diffraction, Condensed matter physics, Charge density, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Condensed Matter::Superconductivity, Lattice (order), 0103 physical sciences, Femtosecond, Condensed Matter::Strongly Correlated Electrons, 010306 general physics, 0210 nano-technology, Charge density wave, Phase diagram
Abstract

The phase diagram of 1$T$-TaS${}_{2}$ involves many different solid-state phases, including several different kinds of charge-density-wave (CDW) phase both commensurate and incommensurate with the underlying lattice. Recent experiments have shown that it is possible to drive transitions between these phases with intense femtosecond pulses of light. This work focuses on the light-driven transition from the nearly commensurate CDW phase to the incommensurate phase, using time-resolved x-ray diffraction. The authors find that the new incommensurate domains grow in a self-similar way. They also employ a double-pump method to study the dynamics and stability of the novel incommensurate phase during growth.

Published
2017
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49. Ultrafast Formation of a Charge Density Wave State in 1T−TaS2 : Observation at Nanometer Scales Using Time-Resolved X-Ray Diffraction

Author

Jeremy A. Johnson, A. Lübcke, Lucas Huber, Vincent Jacques, Benoit Corraze, Gerhard Ingold, Etienne Janod, T. Huber, Vincent Esposito, S. Grübel, M. Kubli, Claire Laulhé, S. O. Mariager, Gabriel Lantz, Paul Beaud, Matteo Savoini, J. Rittmann, Laurent Cario, Steven L. Johnson, Sylvain Ravy, and Andrés Ferrer

Subjects
Diffraction, Phase transition, Materials science, Condensed matter physics, Nucleation, General Physics and Astronomy, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Phase (matter), Picosecond, 0103 physical sciences, Femtosecond, 010306 general physics, 0210 nano-technology, Charge density wave, Excitation
Abstract

Femtosecond time-resolved X-ray diffraction is used to study a photo-induced phase transition between two charge density wave (CDW) states in 1T-TaS$_2$, namely the nearly commensurate (NC) and the incommensurate (I) CDW states. Structural modulations associated with the NC-CDW order are found to disappear within 400 fs. The photo-induced I-CDW phase then develops through a nucleation/growth process which ends 100 ps after laser excitation. We demonstrate that the newly formed I-CDW phase is fragmented into several nanometric domains that are growing through a coarsening process. The coarsening dynamics is found to follow the universal Lifshitz-Allen-Cahn growth law, which describes the ordering kinetics in systems exhibiting a non-conservative order parameter.

Published
2017
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50. Engineering Processes at the Interface of p-Semiconductor for Enhancing the Open Circuit Voltage in p-Type Dye-Sensitized Solar Cells

Author

Yann Pellegrin, Stéphane Jobic, Ludovic Favereau, Errol Blart, Fabrice Odobel, Guy Louarn, Adèle Renaud, Mohammed Boujtita, Laurent Cario, Lionel Hirsch, Aurélien Planchat, Chimie Et Interdisciplinarité : Synthèse, Analyse, Modélisation (CEISAM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Laboratoire de physique des interactions ondes matières (LPIOM), Université Sciences et Technologies - Bordeaux 1-École Nationale Supérieure de Chimie et de Physique de Bordeaux (ENSCPB)-Centre National de la Recherche Scientifique (CNRS), Institut des Matériaux Jean Rouxel (IMN), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), Communication de centre, Institut National de la Recherche Agronomique (INRA), ANR-12-PRGE-0016-01, Agence Nationale de la Recherche, CM1202, European Cooperation in Science and Technology, Région des Pays de la Loire, Laboratoire de l'intégration, du matériau au système (IMS), Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Université Sciences et Technologies - Bordeaux 1, Université Sciences et Technologies - Bordeaux 1-Institut Polytechnique de Bordeaux-Centre National de la Recherche Scientifique (CNRS), Université de Nantes - Faculté des Sciences et des Techniques, Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1-ENSCPB-Centre National de la Recherche Scientifique (CNRS), and Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Spin coating, Materials science, Passivation, Renewable Energy, Sustainability and the Environment, Open-circuit voltage, Non-blocking I/O, Inorganic chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 02 engineering and technology, Electrolyte, engineering.material, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, Dielectric spectroscopy, Dye-sensitized solar cell, Coating, Chemical engineering, engineering, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], General Materials Science, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS
Abstract

International audience; To prevent the interfacial charge recombination between injected holes in the valence band and the redox mediator in the electrolyte in p-type dye sensitized solar cells (p-DSSC) the passivation of the recombination sites by organic insulator chenodeoxycholic acid (CDCA) layer is critically investigated in this study. Rather than classical coating of the semiconductor's surface by simultaneous co-adsorption of CDCA during the dyeing step, two other methods were investigated. The first consists in dissolving CDCA in the electrolyte, while the second consists in spin coating an ethanol solution of CDCA onto the already dyed photocathode. In 2 this study different sensitizers, electrolytes and p-SCs, (NiO, CuGaO2) were explored. Analysis of the current/voltage curves and electrochemical impedance spectroscopy provides evidence that the role of the CDCA layer is to create a physical barrier to prevent the approach of the redox mediator from the NiO surface and consequently raise the Voc. The important finding of this study is the demonstration that the Voc in p-DSSC is heavily limited by interfacial charge recombination and that higher Voc values much above 100 mV and as high as 500 mV can be attained with conventional materials (NiO) if this deleterious side reaction can be suppressed or diminished.

Published
2017
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