45 results on '"Fouchet, Arnaud"'
Search Results
2. Amido bisphosphonic acid as anchoring agent and photopolymerization initiator onto zirconium oxide surface
- Author
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Ben-Hadj-Salem, Jihen, Dragoe, Diana, Marie, Philippe, Froissart, Sandrine, Fouchet, Arnaud, Rouden, Jacques, Lecourt, Jérôme, Harnois, Christelle, Touil, Soufiane, Baudoux, Jérôme, and Lepoittevin, Bénédicte
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- 2023
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3. Modeling of SrTiO3 polycrystalline substrate grain growth for tuning thin film functional properties
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Dallocchio, Marie, Manière, Charles, Lecourt, Jérôme, Lüders, Ulrike, Prellier, Wilfrid, David, Adrian, and Fouchet, Arnaud
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- 2023
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4. Structural, optical, and electrical properties of TiO2 thin films deposited by ALD: Impact of the substrate, the deposited thickness and the deposition temperature
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Jolivet, Aline, Labbé, Christophe, Frilay, Cédric, Debieu, Olivier, Marie, Philippe, Horcholle, Bryan, Lemarié, Franck, Portier, Xavier, Grygiel, Clara, Duprey, Sylvain, Jadwisienczak, Wojciech, Ingram, David, Upadhyay, Mudit, David, Adrian, Fouchet, Arnaud, Lüders, Ulrike, and Cardin, Julien
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- 2023
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5. Tuning the Transparency Window of SrVO3 Transparent Conducting Oxide.
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Cheikh, Aïmane, El khaloufi, Oualyd, Rath, Martando, Lüders, Ulrike, Fouchet, Arnaud, Cardin, Julien, Labbé, Christophe, Prellier, Wilfrid, and David, Adrian
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- 2024
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6. Morphology control of self-organised Sr3V2O8 nanostructures on SrVO3 grown onto single and poly-crystalline subjacent SrTiO3 substrates
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Bérini, Bruno, Dallocchio, Marie, David, Adrian, Lüders, Ulrike, Bourlier, Yoan, Rault, Ludivine, Coq Germanicus, Rosine, Prellier, Wilfrid, Dumont, Yves, Demange, Valérie, and Fouchet, Arnaud
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- 2021
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7. XPS monitoring of SrVO3 thin films from demixing to air ageing: The asset of treatment in water
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Bourlier, Yoan, Frégnaux, Mathieu, Bérini, Bruno, Fouchet, Arnaud, Dumont, Yves, and Aureau, Damien
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- 2021
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8. Antibacterial Zirconia Surfaces from Organocatalyzed Atom-Transfer Radical Polymerization.
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Harfouche, Nesrine, Marie, Philippe, Dragoe, Diana, Le, Hung, Thébault, Pascal, Bilot, Christelle, Fouchet, Arnaud, Rouden, Jacques, Baudoux, Jérôme, and Lepoittevin, Bénédicte
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ZIRCONIUM oxide ,RADICALS (Chemistry) ,X-ray photoelectron spectroscopy ,ATOMIC force microscopes ,CATIONIC polymers ,CONTACT angle - Abstract
Antibacterial coatings are becoming increasingly attractive for application in the field of biomaterials. In this framework, we developed polymer coating zirconia with antibacterial activity using the "grafting from" methodology. First, 1-(4-vinylbenzyl)-3-butylimidazolium chloride monomer was synthesized. Then, the surface modification of zirconia substrates was performed with this monomer via surface-initiated photo atom transfer radical polymerization for antibacterial activity. X-ray photoelectron spectroscopy, ellipsometry, static contact angle measurements, and an atomic force microscope were used to characterize the films for each step of the surface modification. The results revealed that cationic polymers could be successfully deposited on the zirconia surfaces, and the thickness of the grafted layer steadily increased with polymerization time. Finally, the antibacterial adhesion test was used to evaluate the antibacterial activity of the modified zirconia substrates, and we successfully showed the antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa strains. [ABSTRACT FROM AUTHOR]
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- 2024
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9. Study of the electronic phase transition with low dimensionality in SrVO3 thin films
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Fouchet, Arnaud, Allain, Mickaël, Bérini, Bruno, Popova, Elena, Janolin, Pierre-Eymeric, Guiblin, Nicolas, Chikoidze, Ekaterina, Scola, Joseph, Hrabovsky, David, Dumont, Yves, and Keller, Niels
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- 2016
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10. Formation and Etching of the Insulating Sr‐Rich V5+ Phase at the Metallic SrVO3 Surface Revealed by Operando XAS Spectroscopy Characterizations.
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Polewczyk, Vincent, Mezhoud, Moussa, Rath, Martando, El‐Khaloufi, Oualyd, Bassato, Ferdinando, Fouchet, Arnaud, Prellier, Wilfrid, Frégnaux, Mathieu, Aureau, Damien, Braglia, Luca, Vinai, Giovanni, Torelli, Piero, and Lüders, Ulrike
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METALLIC surfaces ,ETCHING ,THIN films ,X-ray absorption ,SPECTROMETRY ,X-ray absorption near edge structure - Abstract
In the search of low cost and more efficient electronic devices, here the properties of SrVO3 transparent conductor oxide (TCO) thin film are investigated, both visible‐range optically transparent and highly conductive, it stands as a promising candidate to substitute the standard indium‐tin‐oxide (ITO) in applications. Its surface stability under water (both liquid and vapor) and other gaseous atmospheres is especially addressed. Through the use of spectroscopy characterizations, X‐ray photoemission and operando X‐ray absorption measurements, the formation of a thin Sr‐rich V5+ layer located at the surface of the polycrystalline SrVO3 film with aging is observed, and for the first time how it can be removed from the surface by solvating in water atmosphere. The surface recovery is associated to an etching process, here spectroscopically characterized in operando conditions, allowing to follow the stoichiometric modification under reaction. Once exposed in oxygen atmosphere, the Sr‐rich V5+ layer forms again. The findings improve the understanding of aging effects in perovskite oxides, allowing for the development of functionalized films in which it is possible to control or to avoid an insulating surface layer. This constitutes an important step towards the large‐scale use of V‐based TCOs, with possible implementations in oxide‐based electronics. [ABSTRACT FROM AUTHOR]
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- 2023
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11. Controlling mesenchymal stem cell differentiation using vanadium oxide thin film surface wettability.
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Khokhlova, Maria, Yadav, Abhishek, Hammad, M., Lhuissier, Eva, Retoux, R., Goux, D., Fouchet, Arnaud, David, Adrian, Luders, Ulrike, Boumediene, Karim, and Prellier, W.
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MESENCHYMAL stem cell differentiation ,MESENCHYMAL stem cells ,OXIDE coating ,VANADIUM oxide ,THIN films - Abstract
Although vanadium compounds are well recognized for their ability to change from insulator to metal, they may also be used therapeutically to address significant medical issues. In this study, we used vanadium oxide thin films synthesized by the pulsed laser deposition (PLD) technique to examine human stem cells generated from bone marrow. According to x-ray reflectivity (XRR) measurements, the films' thickness ranged from 6 to 26 nm. The water contact angle method has been employed to probe the surface energy and wettability of the films, which influence the cell behavior significantly. We also used a variety of techniques, such as differentiation staining, phase contrast microscopy, and real-time reverse transcription-polymerase chain reaction (RT-PCR), to examine the growth, adhesion, proliferation, and differentiation of human bone marrow mesenchymal stem cells (hBMMSCs) on these oxide films over time. Our results indicated that vanadium oxide films alter hBMMSCs adhesion and growth and affect their differentiation. The application of VO
x films in biological and medical materials, as well as future research on cells, is all made possible by these findings, which also improve our understanding of the biological actions of vanadium compounds. [ABSTRACT FROM AUTHOR]- Published
- 2023
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12. Artificial Aging of Thin Films of the Indium-Free Transparent Conducting Oxide SrVO3.
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Rath, Martando, Mezhoud, Moussa, El Khaloufi, Oualyd, Lebedev, Oleg, Cardin, Julien, Labbé, Christophe, Gourbilleau, Fabrice, Polewczyk, Vincent, Vinai, Giovanni, Torelli, Piero, Fouchet, Arnaud, David, Adrian, Prellier, Wilfrid, and Lüders, Ulrike
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- 2023
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13. Pulsed laser deposition and optical characterizations of the magnetic samarium orthoferrite
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Berini, Bruno, Mistrik, Jan, Dumont, Yves, Popova, Elena, Fouchet, Arnaud, Scola, Joseph, and Keller, Niels
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- 2012
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14. IR thermometry: a new tool for contactless in situ investigations of metal–insulator transition
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Berini, Bruno, Fouchet, Arnaud, Popova, Elena, Tessier, Michel, Denise, Stephane, Dumont, Yves, and Keller, Niels
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- 2010
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15. Spontaneous ordering, strain control, and multifunctionality in vertical nanocomposite heteroepitaxial films
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Fouchet, Arnaud, Haiyan Wang, Hao Yang, Jongsik Yoon, Quanxi Jia, and MacManus-Driscoll, Judith Louise
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Barium compounds -- Electric properties ,Barium compounds -- Structure ,Magnesium oxide -- Electric properties ,Samarium -- Electric properties ,Samarium -- Mechanical properties ,Titanium -- Electric properties ,Titanium -- Mechanical properties ,Zirconium -- Electric properties ,Business ,Electronics ,Electronics and electrical industries - Abstract
The strain coupling, microstructural evolution, and functional properties of a series of BaTi[O.sub.3] (BTO) films with different second-phase oxide additions, Ti[O.sub.2], MgO, Zr[O.sub.2], [Sm.sub.2][O.sub.3] and [Y.sub.2][O.sub.3] (YO), is studied. The studies have shown that the strain state in BTO is tuned by different additions and compared with BFO, which is switched from tensile for a pure film on STO to compressive by the presence of the second phase (SmO).
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- 2009
16. Synthesis and transfer of nanosheets seed layer on low cost substrates for complex oxides growth
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Baudouin, Florent, Boileau, Alexis, Dallocchio, Marie, Ollivier, Sophie, Bouquet, Valérie, David, Adrian, Lüders, Ulrike, B. Mercey, Berini, Bruno, Dumont, Yves, Députier, Stéphanie, Prellier, Wilfrid, Guilloux-Viry, Maryline, Fouchet, Arnaud, and Demange, Valérie
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- 2020
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17. Highly Transparent and Conductive Indium‐Free Vanadates Crystallized at Reduced Temperature on Glass Using a 2D Transparent Nanosheet Seed Layer.
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Boileau, Alexis, Hurand, Simon, Baudouin, Florent, Lüders, Ulrike, Dallocchio, Marie, Bérini, Bruno, Cheikh, Aimane, David, Adrian, Paumier, Fabien, Girardeau, Thierry, Marie, Philippe, Labbé, Christophe, Cardin, Julien, Aureau, Damien, Frégnaux, Mathieu, Guilloux‐Viry, Maryline, Prellier, Wilfrid, Dumont, Yves, Demange, Valérie, and Fouchet, Arnaud
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VANADATES ,GLASS ,ELLIPSOMETRY ,SEEDS ,INDIUM ,TEMPERATURE ,TRANSPARENT ceramics - Abstract
Indium‐tin‐oxide (ITO) is a widely employed transparent conducting oxide (TCO), but the indium scarcity and price encourage developing some alternatives. The correlated metals CaVO3 and SrVO3 have been recently identified as new TCOs with functional properties being comparable to ITO. However, their technological potential is limited by the critical requirement of a perovskite structure of the film, impossible to achieve via direct growth on substrates commonly used for applications. In this article, the authors tackle this limitation by demonstrating the crystalline growth of vanadate TCOs on glass at temperatures below 600 °C, with the help of 2D nanosheets as transparent seed layers. The functional properties do not suffer from the textured structure of the films, as confirmed by an in‐depth spectroscopic ellipsometry study, allowing for an industrially viable approach to integrate vanadate TCOs on virtually any surface and to exploit their promising performances as a new generation TCO. [ABSTRACT FROM AUTHOR]
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- 2022
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18. Metastable monoclinic [110] layered perovskite Dy2Ti2O7 thin films for ferroelectric applications
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Pravarthana, Dhanapal, Lebedev, Oleg I., David, Adrian, Fouchet, Arnaud, Trassin, Morgan, Rohrer, Gregory S., Salvador, Paul A., and Prellier, Wilfrid
- Abstract
Using the Combinatorial Substrate Epitaxy (CSE) approach, we report the stabilization of Dy2Ti2O7 epitaxial monoclinic, layered-perovskite phase Dy2Ti2O7 thin films. To achieve this, the films are deposited on high density, polished La2Ti2O7 polycrystalline ceramic substrates, which are stable as monoclinic layered-perovskites, and were prepared by conventional sintering. Microstructural analysis using electron backscatter diffraction (EBSD), electron diffraction (ED), and high-resolution transmission electron microscopy (HRTEM) support this observation. Further, they reveal that the cubic pyrochlore phase is observed far from the interface as films are grown thicker (100 nm), confirming the importance of substrate-induced phase and space group selection. This works reinforces the vast potential of CSE to promote the stabilization of metastable phases, thus giving access to new functional oxide materials, across a range of novel material systems including ferroelectrics., RSC Advances, 9 (35), ISSN:2046-2069
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- 2019
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19. Tuning the metal-insulator transition in epitaxial SrVO3 films by uniaxial strain
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Wang, Changan, Zhang, Hongbin, Deepak, Kumar, Chen, 5Chao, Fouchet, Arnaud, Duan, Juanmei, Hilliard, Donovan, Kentsch, Ulrich, Chen, Deyang, Zeng, Min, Gao, Xingsen, Zeng, Yu-Jia, Helm, Manfred, Prellier, Wilfrid, Zhou, Shengqiang, Institute of Ion Beam Physics and Materials Research [Dresden], Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Technische Universität Dresden = Dresden University of Technology (TU Dresden), Shenzhen University [Shenzhen], Technische Universität Darmstadt - Technical University of Darmstadt (TU Darmstadt), Laboratoire de cristallographie et sciences des matériaux (CRISMAT), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), South China Normal University, École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), Qiongzhou University, Department of Computer Science, Rensselaer Polytechnic Institute (RPI), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), and Johannes Gutenberg - Universität Mainz (JGU)
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[PHYS]Physics [physics] ,Condensed Matter - Materials Science ,Metal-insulator transition ,DFT + DMFT ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,[CHIM.MATE]Chemical Sciences/Material chemistry ,Lattice distortion ,Correlated electrons ,Ion impact & scattering ,[CHIM]Chemical Sciences ,Strain engineering ,Perovskites ,Condensed Matter::Strongly Correlated Electrons ,Oxide thin film ,[PHYS.COND]Physics [physics]/Condensed Matter [cond-mat] ,[PHYS.COND.CM-SCE]Physics [physics]/Condensed Matter [cond-mat]/Strongly Correlated Electrons [cond-mat.str-el] ,ComputingMilieux_MISCELLANEOUS - Abstract
Understanding of the metal-insulator transition (MIT) in correlated transition-metal oxides is a fascinating topic in condensed matter physics and a precise control of such transitions plays a key role in developing novel electronic devices. Here we report an effective tuning of the MIT in epitaxial SrVO3 (SVO) films by expanding the out-of-plane lattice constant without changing in-plane lattice parameters, through helium ion irradiation. Upon increase of the ion fluence, we observe a MIT with a crossover from metallic to insulating state in SVO films. A combination of transport and magnetoresistance measurements in SVO at low temperatures reveals that the observed MIT is mainly ascribed to electron-electron interactions rather than disorder-induced localization. Moreover, these results are well supported by the combination of density functional theory and dynamical mean field theory (DFT+DMFT) calculations, further confirming the decrease of the bandwidth and the enhanced electron-electron interactions resulting from the expansion of out-of-plane lattice constant. These findings provide new insights into the understanding of MIT in correlated oxides and perspectives for the design of unexpected functional devices based on strongly correlated electrons., Comment: 17 pages, 4 figures,submitted to Phys. Rev. Materials
- Published
- 2019
20. Tuning the electronic properties of LaAlO 3 / SrTiO 3 interfaces by irradiating the LaAlO 3 surface with low-energy cluster ion beams
- Author
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Ridier, Karl, Aureau, Damien, Berini, Bruno, Dumont, Yves, Keller, Niels, Vigneron, Jackie, Etcheberry, Arnaud, Domengès, Bernadette, Fouchet, Arnaud, Groupe d'Etude de la Matière Condensée (GEMAC), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Institut Lavoisier de Versailles (ILV), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de cristallographie et sciences des matériaux (CRISMAT), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), and NXP Semiconductors
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[PHYS]Physics [physics] ,Electronic structure ,X-ray photoelectron spectroscopy ,Surface & interfacial phenomena ,Electrical conductivity ,Oxides ,Irradiation effects ,[PHYS.COND]Physics [physics]/Condensed Matter [cond-mat] - Abstract
International audience; We have investigated the effects of low-energy ion beam irradiations using argon clusters on the chemical and electronic properties of LaAlO3/SrTiO3 (LAO/STO) heterointerfaces by combining x-ray photoelectron spectroscopy (XPS) and electrical transport measurements. Due to its unique features, we demonstrate that a short-time cluster ion irradiation of the LAO surface induces significant modifications in the chemical properties of the buried STO substrate with (1) a lowering of Ti atoms oxidation states (from Ti4+ to Ti3+ and Ti2+) correlated to the formation of oxygen vacancies at the LAO surface and (2) the creation of new surface states for Sr atoms. Contrary to what is generally observed by using higher energy ion beam techniques, this leads to an increase of the electrical conductivity at the LAO/STO interface. Our XPS data clearly reveal the existence of dynamical processes on the titanium and strontium atoms, which compete with the effect of the cluster ion beam irradiation. These relaxation effects are in part attributed to the diffusion of the ion-induced oxygen vacancies in the entire heterostructure since an increase of the interfacial metallicity is also evidenced far from the irradiated area. This paper highlights the possibility of tuning the electrical properties of LAO/STO interfaces by surface engineering, confirming experimentally the intimate connection between LAO chemistry and electronic properties of LAO/STO interfaces.
- Published
- 2018
21. Strong Magnetic Anisotropy of Epitaxial PrVO3 Thin Films on SrTiO3 Substrates with Different Orientations.
- Author
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Kumar, Deepak, David, Adrian, Fouchet, Arnaud, Pautrat, Alain, Boullay, Philippe, Jung, Chang Uk, and Prellier, Wilfrid
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- 2020
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22. Ca3(VO4)2 Nanowires on Metallic CaVO3 Films as Nanocapacitors.
- Author
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Demange, Valérie, Bérini, Bruno, Gautier, Brice, Popova, Elena, Dumont, Yves, and Fouchet, Arnaud
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- 2020
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23. Transfer of Epitaxial SrTiO3 Nanothick Layers Using Water-Soluble Sacrificial Perovskite Oxides.
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Bourlier, Yoan, Bérini, Bruno, Frégnaux, Mathieu, Fouchet, Arnaud, Aureau, Damien, and Dumont, Yves
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- 2020
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24. Textured Manganite Films Anywhere.
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Boileau, Alexis, Dallocchio, Marie, Baudouin, Florent, David, Adrian, Lüders, Ulrike, Mercey, Bernard, Pautrat, Alain, Demange, Valérie, Guilloux-Viry, Maryline, Prellier, Wilfrid, and Fouchet, Arnaud
- Published
- 2019
- Full Text
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25. Strontium titanate (100) surfaces monitoring by high temperature in situ ellipsometry
- Author
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Allain, Mickaël, Janolin, Pierre-Eymeric, Guiblin, Nicolas, Chikoidze, Ekaterina, Scola, Joseph, Popova, Elena, Deb, Marwan, Bocher, Laura, Gloter, Alexandre, Stephan, Odile, Warot-Fonrose, Bénédicte, Hrabovsky, David, Berini, Bruno, Fouchet, Arnaud, Aureau, D., Keller, Niels, Etcheberry, A., Dumont, Yves, Groupe d'Etude de la Matière Condensée (GEMAC), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Structures, Propriétés et Modélisation des solides (SPMS), Institut de Chimie du CNRS (INC)-CentraleSupélec-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), Centre d'élaboration de matériaux et d'études structurales (CEMES), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), Institut Lavoisier de Versailles (ILV), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)
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Materials science ,Analytical chemistry ,General Physics and Astronomy ,02 engineering and technology ,Epitaxy ,01 natural sciences ,Overlayer ,Atomic layer deposition ,chemistry.chemical_compound ,X-ray photoelectron spectroscopy ,Ellipsometry ,0103 physical sciences ,Thin film ,[PHYS.COND]Physics [physics]/Condensed Matter [cond-mat] ,ComputingMilieux_MISCELLANEOUS ,010302 applied physics ,Surfaces and Interfaces ,General Chemistry ,[CHIM.MATE]Chemical Sciences/Material chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Surfaces, Coatings and Films ,chemistry ,13. Climate action ,Strontium titanate ,0210 nano-technology ,Layer (electronics) - Abstract
We report monitoring and analysis of the contamination overlayer on the surface of different SrTiO3 (STO) substrates by in situ spectroscopic ellipsometry (SE) and ex situ X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Substrates of STO with different terminations, random and TiO2 terminated, were heated from room temperature up to 720 °C under oxygen pressure in UHV chamber similar to conditions commonly used for epitaxial growth of perovskite oxides. Contamination layer on the substrate was modeled as an equivalent dielectric overlayer with a thickness of 2 nm at room temperature which decreases progressively during the heating up to reach its minimum (around 1 unit cell) at the temperature around 550 °C. After exposition to air, surface recovers a contamination layer on both types of substrates (with random termination and TiO2 termination). XPS analysis confirmed that water and carbon dioxide as adventitious carbon species present in air are chemically adsorbed on the STO surface, providing evidence of desorption process which persists until 550 °C. This condition is an important issue in order to obtain clean controlled interface between STO and deposited film for low temperature growth as for instance atomic layer deposition and integration of STO buffer layer on silicon. In situ SE commonly present in thin layer deposition systems is a powerful tool to monitor in situ surface contamination and decontamination temperature as it can be performed in situ even in operando.
- Published
- 2016
26. Gene Regulatory Network Inference using ensembles of Local Multiple Kernel Models
- Author
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Fouchet, Arnaud, Delosme, Jean-Marc, d'Alché-Buc, Florence, Fouchet, Arnaud, Informatique, Biologie Intégrative et Systèmes Complexes (IBISC), Université d'Évry-Val-d'Essonne (UEVE), Algorithms and Models for Integrative Biology (AMIB ), Laboratoire d'informatique de l'École polytechnique [Palaiseau] (LIX), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Laboratoire de Recherche en Informatique (LRI), Université Paris-Sud - Paris 11 (UP11)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-Inria Saclay - Ile de France, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria), and École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS)-Laboratoire de Recherche en Informatique (LRI)
- Subjects
[SDV.BIBS] Life Sciences [q-bio]/Quantitative Methods [q-bio.QM] ,[INFO.INFO-LG]Computer Science [cs]/Machine Learning [cs.LG] ,[INFO.INFO-LG] Computer Science [cs]/Machine Learning [cs.LG] ,[INFO.INFO-BI]Computer Science [cs]/Bioinformatics [q-bio.QM] ,[SDV.BIBS]Life Sciences [q-bio]/Quantitative Methods [q-bio.QM] ,[INFO.INFO-BI] Computer Science [cs]/Bioinformatics [q-bio.QM] - Abstract
International audience; Reconstructing gene regulatory network from high-throughput data has many potential applications, from understanding a biological organism to identifying potential drug targets. It is also a notoriously difficult problem, tackled by many scientists with various methods. In this paper, we formulate GRN inference as a sparse regression problem. We decompose the prediction of a p-genes system in p different regression problems. For each gene (target gene), we train a kernel-based regression with feature selection, predicting the expression pattern of the target gene using all the other genes (input genes). The regression will give the importance of each input gene in the prediction of the target gene. We take this importance as an indication of a putative regulatory link. Putative links are then aggregated over all genes to provide a ranking of interactions, from which we infer the GRN. Furthermore, biological data are heterogeneous. The method we propose can learn from both steady-state and time-series data, using an ensemble method that can be applied to other regression model. Finally, we compare our method, called LocKING, to state-of-the-art methods on real and realistic datasets, which are widely spread in the GRN inference community. We show that our method is competitive against individual methods. Nevertheless, best results are obtained by integrating multiple methods. We show that using LocKING among other methods significantly enhances the accuracy of the network inferred.
- Published
- 2013
27. Surface Characterizations and Selective Etching of Sr‐Rich Segregation on Top of SrVO3 Thin‐Films Grown by Pulsed Laser Deposition.
- Author
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Bourlier, Yoan, Frégnaux, Mathieu, Bérini, Bruno, Fouchet, Arnaud, Dumont, Yves, and Aureau, Damien
- Subjects
SURFACE morphology ,SURFACE reactions ,PEROVSKITE ,OXIDES ,THIN films ,NANORODS - Abstract
Since SrVO3 (SVO) can be used as a highly conductive material for perovskite heterostructures, the control of surface morphology and chemistry of such thin‐films are essential. Using pulsed laser deposition, two distinct topographies can be produced. Thus, by tuning oxygen pressure in the growth chamber during cooling, smooth or partially covered by self‐oriented Sr3V2O8 nanorods surfaces can be grown. This study manages to correlate the two typical topographies, revealed by atomic force microscopy (AFM), with their chemical compositions obtained by X‐ray photoelectron spectroscopy (XPS). At first, a model describes their initial surface chemistry through the Sr/V cationic ratio and the (Sr+V)/Oox ratio. Furthermore, using sputter‐depth profiling, post‐thermal treatments and wet chemical etching, SVO thin‐film chemical compositions are extensively studied. We demonstrate that they are composed of stoichiometric SVO phase covered by Sr‐rich layer on top. Finally, treatment in water for 180 seconds helps to remove Sr‐rich phases. Sr3V2O8 nanorods are found selectively dissolved leaving a surface nano‐imprint. Moreover, on smooth SVO surfaces, a balanced Sr/V cationic ratio of 1.0±0.1 is obtained. These results appear very promising for SVO thin‐films surface preparation and further development as electrodes for electronic devices. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
28. Strontium Vanadate Deposited by ALD: Toward a New Synthesis Approach.
- Author
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Jolivet, Aline, Cardin, Julien, Cheik, Aiman, Frilay, Cédric, Gourbilleau, Fabrice, Lemarié, Franck, Portier, Xavier, Jadwisienczak, Wojciech, Ingram, David, Mezhoud, Moussa, Lüders, Ulrike, Fouchet, Arnaud, and Labbé, Christophe
- Published
- 2023
- Full Text
- View/download PDF
29. Kernel methods for gene regulatory network inference
- Author
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Fouchet, Arnaud, Informatique, Biologie Intégrative et Systèmes Complexes (IBISC), Université d'Évry-Val-d'Essonne (UEVE), Université d'Evry-Val-d'Essonne, Florence d’Alché-Buc, Jean-Marc Delosme, and Davesne, Frédéric
- Subjects
Exploration de données -- Méthodes statistiques ,Genetic regulation ,[INFO.INFO-LG]Computer Science [cs]/Machine Learning [cs.LG] ,Régulation génétique ,automatic learning ,Data exploration-- statistical methods ,Multiple kernels ,[INFO.INFO-LG] Computer Science [cs]/Machine Learning [cs.LG] ,Dérivées partielles ,Apprentissage automatique ,Noyaux multiples ,[INFO.INFO-BI]Computer Science [cs]/Bioinformatics [q-bio.QM] ,[INFO.INFO-BI] Computer Science [cs]/Bioinformatics [q-bio.QM] - Abstract
New technologies in molecular biology, in particular dna microarrays, have greatly increased the quantity of available data. in this context, methods from mathematics and computer science have been actively developed to extract information from large datasets. in particular, the problem of gene regulatory network inference has been tackled using many different mathematical and statistical models, from the most basic ones (correlation, boolean or linear models) to the most elaborate (regression trees, bayesian models with latent variables). despite their qualities when applied to similar problems, kernel methods have scarcely been used for gene network inference, because of their lack of interpretability. in this thesis, two approaches are developed to obtain interpretable kernel methods. firstly, from a theoretical point of view, some kernel methods are shown to consistently estimate a transition function and its partial derivatives from a learning dataset. these estimations of partial derivatives allow to better infer the gene regulatory network than previous methods on realistic gene regulatory networks. secondly, an interpretable kernel methods through multiple kernel learning is presented. this method, called lockni, provides state-of-the-art results on real and realistically simulated datasets., De nouvelles technologies, notamment les puces à adn, multiplient la quantité de données disponibles pour la biologie moléculaire. dans ce contexte, des méthodes informatiques et mathématiques sont activement développées pour extraire le plus d'information d'un grand nombre de données. en particulier, le problème d'inférence de réseaux de régulation génique a été abordé au moyen de multiples modèles mathématiques et statistiques, des plus basiques (corrélation, modèle booléen ou linéaire) aux plus sophistiqués (arbre de régression, modèles bayésiens avec variables cachées). malgré leurs qualités pour des problèmes similaires, les modèles à noyaux ont été peu utilisés pour l'inférence de réseaux de régulation génique. en effet, ces méthodes fournissent en général des modèles difficiles a interpréter. dans cette thèse, nous avons développé deux façons d'obtenir des méthodes à noyaux interprétables. dans un premier temps, d'un point de vue théorique, nous montrons que les méthodes à noyaux permettent d'estimer, a partir d'un ensemble d'apprentissage, une fonction de transition et ses dérivées partielles de façon consistante. ces estimations de dérivées partielles permettent, sur des exemples réalistes, de mieux identifier le réseau de régulation génique que des méthodes standards. dans un deuxième temps, nous développons une méthode à noyau interprétable grâce à l'apprentissage à noyaux multiples. ce modèle fournit des résultats du niveau de l'état de l'art sur des réseaux réels et des réseaux simulés réalistes.
- Published
- 2014
30. Full spin polarization of complex ferrimagnetic bismuth iron garnet probed by magneto-optical Faraday spectroscopy
- Author
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Bocher , L., Nolan , M., Gloter , A., Chikoidze , E., March , K., Warot-Fonrose , B., Berini , B., Stephan , O., Dumont , Y., Deb , Marwan, Popova , Elena, Fouchet , Arnaud, Keller , Niels, Matériaux, ingénierie et science [Villeurbanne] ( MATEIS ), Université Claude Bernard Lyon 1 ( UCBL ), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique ( CNRS ) -Institut National des Sciences Appliquées de Lyon ( INSA Lyon ), Université de Lyon-Institut National des Sciences Appliquées ( INSA ) -Institut National des Sciences Appliquées ( INSA ), Institute of Northern Engineering, 455 Duckering Bldg, Laboratoire de Physique des Solides ( LPS ), Université Paris-Sud - Paris 11 ( UP11 ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire de Physique des Solides et de Cristallogenèse, CNRS-Université de Versailles St-Quentin en Yvelines, Laboratoire de Physique des Solides et de Cristallogene?se, Centre d'élaboration de matériaux et d'études structurales ( CEMES ), Institut National des Sciences Appliquées - Toulouse ( INSA Toulouse ), Institut National des Sciences Appliquées ( INSA ) -Institut National des Sciences Appliquées ( INSA ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Toulouse III - Paul Sabatier ( UPS ), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées, Groupe d'Etude de la Matière Condensée ( GEMAC ), Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Centre National de la Recherche Scientifique ( CNRS ), Institut de Physique et Chimie des Matériaux de Strasbourg ( IPCMS ), Université de Strasbourg ( UNISTRA ) -Centre National de la Recherche Scientifique ( CNRS ) -Matériaux et nanosciences d'Alsace, Université de Strasbourg ( UNISTRA ) -Université de Haute-Alsace (UHA) Mulhouse - Colmar ( Université de Haute-Alsace (UHA) ) -Institut National de la Santé et de la Recherche Médicale ( INSERM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Strasbourg ( UNISTRA ) -Université de Haute-Alsace (UHA) Mulhouse - Colmar ( Université de Haute-Alsace (UHA) ) -Institut National de la Santé et de la Recherche Médicale ( INSERM ) -Centre National de la Recherche Scientifique ( CNRS ) -Réseau nanophotonique et optique, Université de Strasbourg ( UNISTRA ) -Université de Haute-Alsace (UHA) Mulhouse - Colmar ( Université de Haute-Alsace (UHA) ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Strasbourg ( UNISTRA ), Informatique, Biologie Intégrative et Systèmes Complexes ( IBISC ), Université d'Évry-Val-d'Essonne ( UEVE ), Laboratoire des Matériaux, Surfaces et Procédés pour la Catalyse ( LMSPC ), Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique ( CNRS ), Groupe d'Etude de la Matière Condensée (GEMAC), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Physics ,Condensed matter physics ,Spintronics ,Spin polarization ,Magnetic circular dichroism ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,Magnetization ,symbols.namesake ,Ferrimagnetism ,[ CHIM.MATE ] Chemical Sciences/Material chemistry ,0103 physical sciences ,Faraday effect ,symbols ,Curie temperature ,[PHYS.COND]Physics [physics]/Condensed Matter [cond-mat] ,010306 general physics ,0210 nano-technology ,Energy (signal processing) ,ComputingMilieux_MISCELLANEOUS ,[ PHYS.COND ] Physics [physics]/Condensed Matter [cond-mat] - Abstract
We investigate the spin-dependent electronic density of states near and above the Fermi level in bismuth iron garnet (BIG), Bi${}_{3}$Fe${}_{5}$O${}_{12}$, by magnetic circular dichroism and magneto-optical Faraday spectroscopy. BIG is a recently synthesized material, as its preparation requires special nonequilibrium conditions. Its scientific and applicative interest resides in huge specific Faraday rotation of the incident light, useful for magneto-optic applications. We show experimentally the presence of spin gaps in the conduction band as recently predicted theoretically by Oikawa et al. [T. Oikawa, S. Suzuki, and K. Nakao, J. Phys. Soc. Jpn. 74, 401 (2005)]. In the range of photon energies, where full spin polarization is expected, completely asymmetric Faraday hysteresis loops were observed, similar to those observed in half-metals such as (Pr,La)${}_{0.7}$Ca${}_{0.3}$MnO${}_{3}$ and Fe${}_{3}$O${}_{4}$. These results were modeled using even and odd (with respect to magnetization) contributions into hysteresis loops. The odd contribution appears only in the energy ranges where the density of states is fully spin polarized and vanishes at the Curie temperature. These results open a new perspective for the use of bismuth iron garnet in optic spintronics at room temperature and above.
- Published
- 2013
31. Control of High Quality SrVO3 Electrode in Oxidizing Atmosphere.
- Author
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Bérini, Bruno, Demange, Valérie, Bouttemy, Muriel, Popova, Elena, Keller, Niels, Dumont, Yves, and Fouchet, Arnaud
- Subjects
TRANSITION metal oxides ,PEROVSKITE analysis ,FERROELECTRICITY ,PULSED laser deposition ,METAL-insulator transitions - Abstract
SrVO
3 (SVO) is a model system for strongly correlated oxides and is highly promising as conductive layer in heterostructures. Therefore, the control of electronic properties and morphology are essential for the advanced applications. Here, the oxygen stability during and after the deposition is explored, as SVO film is expected to undergo different postdeposition thermal and atmosphere treatments during its integration in a heterostructure. Hence, the influence of oxygen stability on morphology and electrical properties of the metallic SrVO3 grown by pulsed laser deposition has been investigated. Films grown under vacuum (SrVO3− δ ) exhibit a very smooth surface while films grown under higher oxygen pressure roughen and present nanostructures at the surface. These nanostructures are found to be of Sr3 V2 O8 phase and their apparition can be controlled by the oxygen supply. Subsequent thermal treatments at different temperatures under same oxygen pressure prevent formation of the Sr3 V2 O8 phase, lead to the stoichiometric SrVO3 , and thus improve the transport properties. In this study is shown the extreme sensitivity of SVO to oxygen and the conditions to obtain high quality smooth SVO films with improved electrical properties for electrode application. [ABSTRACT FROM AUTHOR]- Published
- 2016
- Full Text
- View/download PDF
32. Interface chemical and electronic properties of LaAlO3/SrVO3 heterostructures.
- Author
-
Fouchet, Arnaud, Rault, Julien E., Allain, Mickaël, Bérini, Bruno, Rueff, Jean-Pascal, Dumont, Yves, and Keller, Niels
- Subjects
- *
PHOTOELECTRON spectroscopy , *CHEMICAL properties , *ELECTRIC properties , *PHOTOEMISSION , *ELECTRON emission - Abstract
We have studied the chemical and electronic properties of LaAlO3/SrVO3 (SVO) ultrathin films by combining hard x-ray photoemission spectroscopy and transport measurements. We compare single SrVO3 (SVO) ultrathin films and SrVO3 buried below a polar LaAlO3 (LAO) thin layer, both epitaxially grown on SrTiO3. While ultrathin films (4 unit cells) of SVO do show insulating behavior over the entire temperature range, the LAO/SVO interface has a resistivity minimum at 250 K. When increasing the SVO layer thickness, the minimum is observed to shift to higher temperatures, but the resistivity always stays smaller than that of comparable SVO single films. Hard x-ray photoemission spectroscopy reveals a surface or interface related V5+ component in the V
2p spectra for SVO films and LAO/SVO heterostructures, respectively, attributed to a strongly oxidized component. This chemical reconstruction is weaker in LAO/SVO heterostructures compared to single SVO films. We show that this dead layer in SVO ultrathin films has to be considered when the film thickness reaches the few unit-cells limit and propose solutions on how to prevent this detrimental effect. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
33. In situ optical characterization of metal-insulator transition in LaNiO3 and SrTiO3 perovskites in pulsed laser deposition chamber.
- Author
-
Berini, Bruno, Evain, Maxime, Fouchet, Arnaud, Dumont, Yves, Popova, Elena, and Keller, Niels
- Subjects
METAL-insulator transitions ,LANTHANUM compounds ,STRONTIUM compounds ,OPTICAL properties ,PEROVSKITE ,PULSED laser deposition ,MICROFABRICATION - Abstract
In situ optical characterizations of metal-insulator (MI) transition have been developed in a pulsed laser deposition (PLD) chamber. It consists of associating a spectroscopic ellipsometer and an infrared camera. The first one is sensitive to modifications of the optical indexes and the second one to the emissivity changes. We focus onto the metallic LaNiO3 and the insulating SrTiO3, which present opposite electrical properties as a function of their oxygen content. Using a combinatorial synthesis approach during fabrication by PLD onto LaAlO3 substrate, we observe the evolution of the apparent temperature for different area corresponding to single LaNiO3 or SrTiO3 layers and heterostructures during reduction and reoxygenation process at constant temperature. Thus, the possibility to grow off-stochiometric samples by PLD or to reduce them by heating under high vacuum, associated to the ability of injecting controlled quantity of oxygen by pulsed valve, provide us an original tool in order to study the (MI) transition. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
34. Strain control and spontaneous phase ordering in vertical nanocomposite heteroepitaxial thin films.
- Author
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MacManus-Driscoll, Judith L., Zerrer, Patrick, Haiyan Wang, Hao Yang, Jongsik Yoon, Fouchet, Arnaud, Rong Yu, Blamire, Mark G., and Quanxi Jia
- Subjects
THIN films ,STRAINS & stresses (Mechanics) ,FERROELECTRIC thin films ,SEMICONDUCTORS ,NANOSTRUCTURES - Abstract
Two-phase, vertical nanocomposite heteroepitaxial films hold great promise for (multi)functional device applications. In order to achieve practical devices, a number of hurdles need to be overcome, including the creation of ordered structures (and their formation on a large scale), achieving different combinations of materials and control of strain coupling between the phases. Here we demonstrate major advances on all these fronts: remarkable spontaneously ordered structures were produced in newly predicted compositions, vertical strain was proven to dominate the strain state in films above 20 nm thickness and strain manipulation was demonstrated by selection of phases with the appropriate elastic moduli. The work opens up a new avenue for strain control in relatively thick films and also promises new forms of ordered nanostructures for multifunctional applications. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
35. Magnetic properties of the magnetophotonic crystal based on bismuth iron garnet.
- Author
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Popova, Elena, Magdenko, Liubov, Niedoba, Halina, Deb, Marwan, Dagens, Béatrice, Berini, Bruno, Vanwolleghem, Mathias, Vilar, Christèle, Gendron, François, Fouchet, Arnaud, Scola, Joseph, Dumont, Yves, Guyot, Marcel, and Keller, Niels
- Subjects
MAGNETISM ,GARNET ,MAGNETIC properties ,PHOTOELECTROMAGNETIC effects ,MAGNETIZATION - Abstract
This article reports on the magnetism of continuous and patterned bismuth iron garnet (Bi3Fe5O12 or BIG) thin films for magnetophotonic crystal (MPC) applications. The exact knowledge of the magnetic properties is crucial for the design of fully functional MPC. BIG thin films were grown on several types of isostructural substrates by pulsed laser deposition. The growth conditions and bismuth transfer were optimized to obtain good quality magneto-optically active films compatible with nanostructuring process. MPC were successfully fabricated from BIG/GGG(001) films with low roughness and high Faraday rotation. Magnetic characteristics (magnetization, anisotropy, magnetic domains, magnetization reversal) of the continuous BIG films and MPC were extensively studied and compared to the results of the micromagnetic simulations performed for MPC with different anisotropy. The present study shows that the fabrication of the MPC structure lowers the magnetocrystalline and uniaxial in-plane anisotropies and induces a partial out-of-plane magnetization. External field smaller than 2000 G is sufficient to ensure the out-of-plane saturation of magnetization for optimum device operation, in agreement with micromagnetic calculations. The experimentally determined magnetic properties of MPC are fully compatible with the device operation. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
36. Impact of the Growth Mechanisms on Si and Glass Substrates on the Structural, Optical and Electrical Properties of Anatase TiO2 Thin Films Synthetized By ALD Technique (Oral).
- Author
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Jolivet, Aline, Labbé, Christophe, Frilay, Cédric, Debieu, Olivier, Marie, Philippe, Lemarié, Franck, Portier, Xavier, Grygiel, Clara, Mudit Upadhyay, David, Adrian, Fouchet, Arnaud, Lüders, Ulrike, and Cardin, Julien
- Published
- 2021
- Full Text
- View/download PDF
37. Tuning of the Optical Properties of the Transparent Conducting Oxide SrVO3 by Electronic Correlations.
- Author
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Boileau, Alexis, Cheikh, Aïmane, Fouchet, Arnaud, David, Adrian, Labbé, Christophe, Marie, Philippe, Gourbilleau, Fabrice, and Lüders, Ulrike
- Subjects
VANADATES ,ELECTRIC properties of semiconductors ,THIN films - Abstract
The vanadate SrVO3 is a transparent conductor perovskite with optical and electrical properties competing with those of the most‐used indium tin oxide material. Although its charge density is comparable to that of metals, SrVO3 shows a plasma frequency below the visible range due to strong electronic correlations characterizing the electronic transport in this material and enhancing the effective mass. Therefore, the well‐known interplay between the structure and the electronic properties of strongly correlated systems can be used in such transparent conductor to tune the optical properties, as the plasma frequency also depends on the effective mass. In this study, SrVO3 films are grown by pulsed laser deposition onto different lattice mismatched perovskite substrates such as SrTiO3, LaAlO3, and (LaAlO3)0.3(Sr2TaAlO6)0.7 at different growth temperatures. The structural, electronic, and optical properties are analyzed, illustrating the influence of the strain on the structure of the films and on a shift of the plasma frequency. The electronic correlations in this new group of transparent conducting oxides can be therefore used as a supplementary lever for the tuning of the functional properties. SrVO3 thins films are grown by pulsed laser deposition onto SrTiO3, LaAlO3, and (LaAlO3)0.3(Sr2TaAlO6)0.7. Both optical and electrical properties of the films are investigated and demonstrate that such strongly correlated system is competing with the indium tin oxide as new transparent conducting oxide. The plasma frequency of the films depends on the substrate and can be easily tuned toward the infrared region. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
38. Full spin polarization of complex ferrimagnetic bismuth iron garnet probed by magneto-optical Faraday spectroscopy.
- Author
-
Deb, Marwan, Popova, Elena, Fouchet, Arnaud, and Keller, Niels
- Subjects
- *
NATIVE element minerals , *SILICATE minerals , *SPECTRUM analysis , *ELECTROMAGNETIC induction , *MAGNETISM - Abstract
We investigate the spin-dependent electronic density of states near and above the Fermi level in bismuth iron garnet (BIG), Bi3Fe5O12, by magnetic circular dichroism and magneto-optical Faraday spectroscopy. BIG is a recently synthesized material, as its preparation requires special nonequilibrium conditions. Its scientific and applicative interest resides in huge specific Faraday rotation of the incident light, useful for magneto-optic applications. We show experimentally the presence of spin gaps in the conduction band as recently predicted theoretically by Oikawa et al. [T. Oikawa, S. Suzuki, and K. Nakao, J. Phys. Soc. Jpn. 74, 401 (2005)]. In the range of photon energies, where full spin polarization is expected, completely asymmetric Faraday hysteresis loops were observed, similar to those observed in half-metals such as (Pr,La)0.7Ca0.3MnO3 and Fe3O4. These results were modeled using even and odd (with respect to magnetization) contributions into hysteresis loops. The odd contribution appears only in the energy ranges where the density of states is fully spin polarized and vanishes at the Curie temperature. These results open a new perspective for the use of bismuth iron garnet in optic spintronics at room temperature and above. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
39. Zirconia surface polymer grafting via dopamine-assisted co-deposition and radical photopolymerization.
- Author
-
Dezanet, Clément, Dragoe, Diana, Marie, Philippe, Harfouche, Nesrine, Froissart, Sandrine, Fouchet, Arnaud, Rouden, Jacques, Lecourt, Jérôme, Harnois, Christelle, Thébault, Pascal, Baudoux, Jérôme, and Lepoittevin, Bénédicte
- Subjects
- *
PHOTOPOLYMERIZATION , *METHYL methacrylate , *ZIRCONIUM oxide , *X-ray photoelectron spectroscopy , *GRAFT copolymers , *SURFACE analysis , *CONTACT angle - Abstract
Zirconia surfaces were functionalized by polymer grafting according to a simple and successful two-steps procedure. In the first step, the initiator bearing a N , N -dimethyl amine group was grafted on the surface by co-deposition with dopamine. Secondly, different monomers such as styrene, methyl methacrylate, 2-hydroxyethylmethacrylate, 2,2,2-trifluoroethyl methacrylate and styrene sulfonate were polymerized on the surface using photochemical activation. The efficiency of the two steps, initiator grafting and photopolymerization, were checked by several analytical techniques including X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (SE) and water contact angle measurements. Theses characterizations highlighted the surface chemical change after each step and the possibility to modulate surface hydrophilicity and hydrophobicity by grafting-from polymerizations. [Display omitted] • A novel initiator for radical photopolymerization bearing a catechol group was prepared by a simple two-step procedure. • Zirconia surfaces were functionalized by grafting of a polymer layer using photopolymerization with blue led activation. • The hydrophilicity and hydrophobicity of zirconia surfaces could be modulated according to the nature of the monomer used. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
40. Three dimensional resistance mapping of self-organized Sr3V2O8 nanorods on metallic perovskite SrVO3 matrix.
- Author
-
Germanicus, Rosine Coq, Bourlier, Yoan, Notot, Vincent, Bérini, Bruno, Demange, Valérie, Berthe, Maxime, Boileau, Alexis, Euchin, Matthieu, Dumont, Yves, Aureau, Damien, Fregnaux, Mathieu, Grandidier, Bruno, Lüders, Ulrike, David, Adrian, Prellier, Wilfrid, Biadala, Louis, and Fouchet, Arnaud
- Subjects
- *
ATOMIC force microscopy , *ELECTRON energy loss spectroscopy , *ANNEALING of metals , *SCANNING tunneling microscopy , *SCANNING force microscopy , *NANORODS , *TUNNEL design & construction , *PEROVSKITE - Abstract
• Self organized epitaxial Sr 3 V 2 O 8 nanorods on SrVO 3 metallic matrix. • Specific local electric properties by conductive Atomic Force Microscopy and scanning tunneling microscopy. • Three dimensional resistance mapping of the nanorods by 3D-Spreading Resistance Microscopy mode. Self-organized epitaxial nanorods, obtained by an adapted annealing process after deposition of metallic strontium vanadate perovskite (SrVO 3) thin films, are analyzed to determine their structural, chemical and electrical properties. After the identification of the Sr 3 V 2 O 8 phase of the nanorods by electron diffraction; Electron Energy Loss Spectroscopy investigations show the vanadium oxidation state (V5+) for the nanorods. Two scanning probe techniques are deployed to determine the specific local electrical properties of these Sr 3 V 2 O 8 nanorods. In ambient conditions, local electrical properties are studied by Scanning Spreading Resistance Microscopy based on an Atomic Force Microscope and multiple probe scanning tunneling microscopy is used for the study in ultrahigh vacuum. Both techniques reveal that local electrical resistances of the nanorods are five order of magnitude higher than the resistance of the perovskite SrVO 3 matrix. Futhermore, the nanorods are found to be etched by repeating scanning of the conductive Atomic Force Microcopy probe, enabling a three-dimensional depth profile of the nanorods resistance with 3D-Spreading Resistance Microscopy mode. A partial embedding of the nanorods in the underlying SrVO 3 film is proved and the impact of the water meniscus at the origin of the selective etching observed during Scanning Spreading Resistance Microscopy, in ambient conditions, is discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
41. Tuning the electronic properties of LaAlO3/SrTiO3 interfaces by irradiating the LaAlO3 surface with low-energy cluster ion beams.
- Author
-
Ridier, Karl, Aureau, Damien, Bérini, Bruno, Dumont, Yves, Keller, Niels, Vigneron, Jackie, Etcheberry, Arnaud, Domengès, Bernadette, and Fouchet, Arnaud
- Subjects
- *
ION beams , *ELECTRIC properties , *ELECTRIC conductivity - Abstract
We have investigated the effects of low-energy ion beam irradiations using argon clusters on the chemical and electronic properties of LaAlO 3 / SrTiO 3 (LAO/STO) heterointerfaces by combining x-ray photoelectron spectroscopy (XPS) and electrical transport measurements. Due to its unique features, we demonstrate that a short-time cluster ion irradiation of the LAO surface induces significant modifications in the chemical properties of the buried STO substrate with (1) a lowering of Ti atoms oxidation states (from Ti 4 + to Ti 3 + and Ti 2 + ) correlated to the formation of oxygen vacancies at the LAO surface and (2) the creation of new surface states for Sr atoms. Contrary to what is generally observed by using higher energy ion beam techniques, this leads to an increase of the electrical conductivity at the LAO/STO interface. Our XPS data clearly reveal the existence of dynamical processes on the titanium and strontium atoms, which compete with the effect of the cluster ion beam irradiation. These relaxation effects are in part attributed to the diffusion of the ion-induced oxygen vacancies in the entire heterostructure since an increase of the interfacial metallicity is also evidenced far from the irradiated area. This paper highlights the possibility of tuning the electrical properties of LAO/STO interfaces by surface engineering, confirming experimentally the intimate connection between LAO chemistry and electronic properties of LAO/STO interfaces. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
42. Tuning the Transparency Window of SrVO 3 Transparent Conducting Oxide.
- Author
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Cheikh A, El Khaloufi O, Rath M, Lüders U, Fouchet A, Cardin J, Labbé C, Prellier W, and David A
- Abstract
Correlated transparent conducting oxides (TCOs) have gained great attention, because of their unique combination of transparency and metallic character. SrVO
3 (SVO) was identified as a high-performance TCO in the visible range. Few studies have investigated band structure engineering through chemical doping to enhance the optical properties of SVO. Here, we use two different strategies by exploiting the band-filling and width of the bands derived from Vanadium to tune the screened plasma frequency ωp * and the interband transition Ep - d energy, corresponding to the optical transparency window edges. For control of the band-filling strategy, it is found that Titanium doped SVO has a wide transparency window, but such a composition does not maintain the high electrical conductivity required for TCO applications. Concerning the bandwidth strategy, the doping of SrVO3 by Calcium shows that ωp * remains located in the IR range (1.12 eV), while Ep - d is blue-shifted into the UV region (3.43 eV) due to reinforced electronic correlations. By an appropriate choice of dopant, we successfully increased the size of the transparency window by around 11% from 1.94 eV (SVO) to 2.30 eV (Calcium-doped SVO), while retaining high conductivity of around 2.30 × 104 (S·cm-1 ) and high charge carrier density of 2.93 × 1022 cm-3 .- Published
- 2024
- Full Text
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43. Artificial Aging of Thin Films of the Indium-Free Transparent Conducting Oxide SrVO 3 .
- Author
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Rath M, Mezhoud M, El Khaloufi O, Lebedev O, Cardin J, Labbé C, Gourbilleau F, Polewczyk V, Vinai G, Torelli P, Fouchet A, David A, Prellier W, and Lüders U
- Abstract
SrVO
3 (SVO) is a prospective candidate to replace the conventional indium tin oxide (ITO) among the new generation of transparent conducting oxide (TCO) materials. In this study, the structural, electrical, and optical properties of SVO thin films, both epitaxial and polycrystalline, are determined during and after heat treatments in the 150-250 °C range and under ambient environment in order to explore the chemical stability of this material. The use of these relatively low temperatures speeds up the natural aging of the films and allows following the evolution of their related properties. The combination of techniques rather sensitive to the film surface and of techniques sampling the film volume will emphasize the presence of a surface oxidation evolving in time at low annealing temperatures, whereas the perovskite phase is destroyed throughout the film for treatments above 200 °C. The present study is designed to understand the thermal degradation and long-term stability issues of vanadate-based TCOs and to identify technologically viable solutions for the application of this group as new TCOs.- Published
- 2023
- Full Text
- View/download PDF
44. Strong Magnetic Anisotropy of Epitaxial PrVO 3 Thin Films on SrTiO 3 Substrates with Different Orientations.
- Author
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Kumar D, David A, Fouchet A, Pautrat A, Boullay P, Jung CU, and Prellier W
- Abstract
We have probed the structural and magnetic properties of PrVO
3 (PVO) thin films grown on the (001)-, (110)-, and (111)-oriented SrTiO3 (STO) substrates. By changing the substrate orientation, the film out-of-plane orientation can be tuned to [110], [100]/[010], and [011]/[311], with different in-plane crystallographic variants. Accommodation of these variants on the different substrates implies different strain states, which have direct influence on the magnetic properties of PVO films. The magnetic moment of PVO films radically enhances from 0.4 μB /f.u. for STO(001) to 2.3 μB /f.u. for STO(111). While films on the (001)-oriented STO substrate display out-of-plane anisotropy, an in-plane anisotropy is observed for films grown on the (110)- and (111)-oriented STO substrates. In addition, a strong uniaxial magnetic anisotropy is also extracted for a partially relaxed film on the (110)-oriented STO substrate. Such findings can help oxide community for the better understanding of magnetic anisotropy in vanadate thin films, a subject that still suffer from significant lack of scientific investigations.- Published
- 2020
- Full Text
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45. Transfer of Epitaxial SrTiO 3 Nanothick Layers Using Water-Soluble Sacrificial Perovskite Oxides.
- Author
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Bourlier Y, Bérini B, Frégnaux M, Fouchet A, Aureau D, and Dumont Y
- Abstract
The integration of functional thin film materials with adaptable properties is essential for the development of new paradigms in information technology. Among them, complex oxides with perovskite structures have huge potential based on the particularly vast diversity of physical properties. Here, we demonstrate the possibility of transferring perovskite oxide materials like SrTiO
3 onto a silicon substrate using an environmentally friendly process at the nanoscale by means of a water-soluble perovskite sacrificial layer, SrVO3 . Based on in situ monitoring atomic force microscopy and photoemission studies, we reveal that the dissolution is initiated from a strontium-rich phase at the extreme surface of SrVO3 . The nanothick SrTiO3 -transferred layer onto silicon presents appropriate morphology and monocrystalline quality, providing a proof of concept for the integration and development of all-perovskite-oxide electronics or "oxitronics" onto any Si-based substrate.- Published
- 2020
- Full Text
- View/download PDF
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