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Your search keyword '"Université de Genève = University of Geneva (UNIGE)"' showing total 11 results
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11 results on '"Université de Genève = University of Geneva (UNIGE)"'

1. Many-body parametric resonances in the driven sine-Gordon model

Author

Lovas, Izabella, Citro, Roberta, Demler, Eugene, Giamarchi, Thierry, Knap, Michael, Orignac, Edmond, Kavli Institute for Theoretical Physics [Santa Barbara] (KITP), University of California [Santa Barbara] (UC Santa Barbara), University of California (UC)-University of California (UC), Dipartamento di Fisica 'E. R. Caianiello', Università degli Studi di Salerno = University of Salerno (UNISA)-SuPerconducting and other INnovative materials and devices institute (SPIN-CNR), INFN Sezione di Napoli-Gruppo Collegato di Salerno, Department of Physics [Harvard], Harvard University, Department of Quantum Matter Physics [Geneva] (DQMP), Université de Genève = University of Geneva (UNIGE), Technische Universität Munchen - Université Technique de Munich [Munich, Allemagne] (TUM), Laboratoire de Physique de l'ENS Lyon (Phys-ENS), and École normale supérieure de Lyon (ENS de Lyon)-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)

Subjects
semiclassical, higher-order, FOS: Physical sciences, gap, parametric, Wigner, dimension, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], oscillator, correlation function, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], capture, many-body systems, Quantum Physics, density, sine-Gordon model, variational, parametric resonance, suppression, Hamiltonian, resonance, Quantum Gases (cond-mat.quant-gas), correlation, many-body problem, time dependence, Quantum Physics (quant-ph), Condensed Matter - Quantum Gases, absorption, energy
Abstract

We study a quantum many-body variant of the parametric oscillator, by investigating the driven sine-Gordon model with a modulated tunnel coupling via a semi-classical Truncated Wigner Approximation (TWA). We first analyze the parametric resonant regime for driving protocols that retain our model gapped, and compare the TWA to a Time-Dependent Gaussian Variational Ansatz (TGVA). We then turn to a drive which closes the gap, resulting in an enhanced energy absorption. While the TGVA approach breaks down in this regime, we can apply TWA to explore the dynamics of the mode-resolved energy density, and the higher-order correlations between modes in the prethermal heating regime. For weak driving amplitude, we find an exponentially fast energy absorption in the main resonant mode, while the heating of all remaining modes is almost perfectly suppressed on short time scales. At later times, the highly excited main resonance provides effective resonant driving terms for its higher harmonics through the non-linearities in the Hamiltonian, and gives rise to an exponentially fast heating in these particular modes. We capture the strong correlations induced by these resonant processes by evaluating higher order connected correlation functions. Our results can be experimentally probed in ultracold atomic settings, with parallel one-dimensional quasi-condensates in the presence of a modulated tunnel coupling., 19 pages, 10 figures (including appendix), minor edits, discussion in Sec. IVB extended

Published
2022

2. Strain tuning of interorbital correlations in LaVO3 thin films

Author

Thomas Prokscha, Zaher Salman, Michel Viret, Andreas Suter, D. van der Marel, H. Meley, Stefano Gariglio, M. K. Tran, Jonas A. Krieger, Jérémie Teyssier, Department of Quantum Matter Physics [Geneva] (DQMP), Université de Genève = University of Geneva (UNIGE), Laboratory for Muon-Spin Spectroscopy (LMU), Paul Scherrer Institute (PSI), Laboratorium für Festkorperphysik [ETH Zürich], Departement Physik [ETH Zürich] (D-PHYS), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Laboratoire Nano-Magnétisme et Oxydes (LNO), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay

Subjects
[PHYS]Physics [physics], Materials science, Condensed matter physics, Charge (physics), ddc:500.2, 02 engineering and technology, Electronic structure, Muon spin spectroscopy, 021001 nanoscience & nanotechnology, Polarization (waves), 01 natural sciences, Condensed Matter::Materials Science, Ellipsometry, 0103 physical sciences, Thin film, 010306 general physics, 0210 nano-technology, Spin (physics), Phase diagram
Abstract

$3{d}^{2}$ vanadate perovskites exhibit an unusual phase diagram where the low temperature orbital and spin orders are strongly dependent upon the rare-earth cation size. Here, we demonstrate the delicate role of strain in epitaxial ${\mathrm{LaVO}}_{3}$ films by performing low-energy muon spin spectroscopy and ellipsometry measurements. The electronic structure is revealed by the measurement of the multipeak structure of the charge excitations. The analysis highlights the independent roles of the ${d}_{xy}$ band confinement and the ${d}_{zx},{d}_{zy}$ doublet polarization for the orbital ordering to establish.

Published
2021

3. Covariance Bell inequalities

Author

Flavien Hirsch, Victor Pozsgay, Cyril Branciard, Nicolas Brunner, École normale supérieure de Lyon (ENS de Lyon), Nanophysique et Semiconducteurs (NEEL - NPSC), 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]), Université de Genève = University of Geneva (UNIGE), École normale supérieure - Lyon (ENS Lyon), Nanophysique et Semiconducteurs (NPSC), and Université de Genève (UNIGE)

Subjects
[PHYS]Physics [physics], Physics, Quantum Physics, Inequality, media_common.quotation_subject, FOS: Physical sciences, ddc:500.2, Covariance, 01 natural sciences, 010305 fluids & plasmas, Nonlinear system, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], 0103 physical sciences, Applied mathematics, Quantum Physics (quant-ph), 010306 general physics, Quantum, Random variable, ComputingMilieux_MISCELLANEOUS, Randomness, media_common
Abstract

We introduce Bell inequalities based on covariance, one of the most common measures of correlation. Explicit examples are discussed, and violations in quantum theory are demonstrated. A crucial feature of these covariance Bell inequalities is their nonlinearity; this has nontrivial consequences for the derivation of their local bound, which is not reached by deterministic local correlations. For our simplest inequality, we derive analytically tight bounds for both local and quantum correlations. An interesting application of covariance Bell inequalities is that they can act as "shared randomness witnesses": specifically, the value of the Bell expression gives device-independent lower bounds on both the dimension and the entropy of the shared random variable in a local model., 15 pages, 3 figures

Published
2017

4. One dimensional bosons: From condensed matter systems to ultracold gases

Author

Roberta Citro, Edmond Orignac, Marcos Rigol, Miguel A. Cazalilla, Thierry Giamarchi, Donostia International Physics Center (DIPC), University of the Basque Country [Bizkaia] (UPV/EHU), Centro de Fisica de Materiales (CFM), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Dipartamento di Fisica 'E. R. Caianiello', Università degli Studi di Salerno (UNISA), Département de Physique de la Matière Condensée (DPMC), Université de Genève (UNIGE), Laboratoire de Physique de l'ENS Lyon (Phys-ENS), École normale supérieure - Lyon (ENS Lyon)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, Department of Physics, Georgetown University, University of the Basque Country/Euskal Herriko Unibertsitatea (UPV/EHU), Università degli Studi di Salerno = University of Salerno (UNISA), Université de Genève = University of Geneva (UNIGE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Georgetown University [Washington] (GU), and École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL)

Subjects
Josephson effect, Josephson junctions, [PHYS.COND.GAS]Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], spin chains & ladders: 4He in nanopores, FOS: Physical sciences, General Physics and Astronomy, ddc:500.2, 01 natural sciences, 010305 fluids & plasmas, Condensed Matter - Strongly Correlated Electrons, Tonks–Girardeau gas, Luttinger liquid, Liquid state, Dimension (vector space), Quantum mechanics, 0103 physical sciences, Lieb–Liniger model, 010306 general physics, Mott & Anderson localization of bosons, Boson, Condensed Matter::Quantum Gases, Physics, Strongly Correlated Electrons (cond-mat.str-el), Condensed matter physics, PACS: 67.85.-d, 75.10.Pq, 71.10.Pm, 74.78.-w, cold atoms, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, integrable models, Quantum Gases (cond-mat.quant-gas), Condensed Matter::Strongly Correlated Electrons, [PHYS.COND.CM-SCE]Physics [physics]/Condensed Matter [cond-mat]/Strongly Correlated Electrons [cond-mat.str-el], Condensed Matter - Quantum Gases
Abstract

The physics of one-dimensional interacting bosonic systems is reviewed. Beginning with results from exactly solvable models and computational approaches, the concept of bosonic Tomonaga-Luttinger liquids relevant for one-dimensional Bose fluids is introduced, and compared with Bose-Einstein condensates existing in dimensions higher than one. The effects of various perturbations on the Tomonaga-Luttinger liquid state are discussed as well as extensions to multicomponent and out of equilibrium situations. Finally, the experimental systems that can be described in terms of models of interacting bosons in one dimension are discussed. © 2011 American Physical Society.

Published
2011

5. Nonlocal interference and Hong-Ou-Mandel collisions of single Bogoliubov quasiparticles

Author

Thibaut Jonckheere, Thomas Martin, Jérôme Rech, Dario Ferraro, Departement de Physique Théorique [Genève], Université de Genève (UNIGE), Centre de Physique Théorique - UMR 7332 (CPT), Aix Marseille Université (AMU)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), CPT - E6 Nanophysique, Aix Marseille Université (AMU)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), ANR-10-BLAN-0412,1shot,Optique quantique électronique : expériences d' Hanbury-Brown Twiss et d'Hong Ou Mandel avec des sources d'électrons uniques(2010), ANR-14-CE32-0017,1 shot reloaded,Optique quantique électronique : effets à N corps à l'échelle de quelques particules(2014), and Université de Genève = University of Geneva (UNIGE)

Subjects
Electronic, Optical and Magnetic Materials, Condensed Matter Physics, Condensed Matter::Quantum Gases, Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Wave packet, Quantum point contact, FOS: Physical sciences, Electron, Fermion, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 73.23.−b, 72.70.+m, 42.50.−p, 74.45.+c, Andreev reflection, [PHYS.COND.CM-S]Physics [physics]/Condensed Matter [cond-mat]/Superconductivity [cond-mat.supr-con], MAJORANA, Condensed Matter::Superconductivity, Quantum electrodynamics, Quantum mechanics, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Electronic, Quasiparticle, Optical and Magnetic Materials, [PHYS.COND.CM-MSQHE]Physics [physics]/Condensed Matter [cond-mat]/Mesoscopic Systems and Quantum Hall Effect [cond-mat.mes-hall], Majorana fermion
Abstract

We consider a device which allows to create and probe single Majorana fermions, in the form of Bogoliubov quasiparticles. It is composed of two counter-propagating edge channels, each put in proximity with a superconducting region where Andreev reflection operates, and which thus converts electrons into Bogoliubov quasiparticles. The edge channels then meet at a quantum point contact where collisions can be achieved. A voltage biased version of the setup was studied in Phys. Rev. Lett. 112, 070604 (2014) and showed non-local interference phenomena and signatures of Bogoliubov quasiparticle collisions in the high frequency noise characteristics at the output, constituting an evidence of the Majorana fermion nature of these excitations. Here, voltage biased leads are replaced by single electron sources in order to achieve collisions of single Bogoliubov quasiparticles, with the major advantage that zero-frequency noise measurements are sufficient to access the intimate nature of Bogoliubov wave-packets. We compute the injection parameters of the source, and go on to investigate the Hanbury-Brown and Twiss and Hong-Ou-Mandel signal at the output, as a function of the mixing angle which controls the electron/hole component of the Bogoliubov wave-packet. In particular, information on the internal structure of the Bogoliubov quasiparticle can be recovered when such a quasiparticle collides with a pure electron. Experimental feasibility with singlet or triplet superconductors is discussed., Comment: 12 pages, 4 figures

Published
2015

6. Distributions of electron waiting times in quantum-coherent conductors

Author

Géraldine Haack, Mathias Albert, Christian Flindt, Laboratory of Quantum Theory (GT), PHotonique, ELectronique et Ingénierie QuantiqueS (PHELIQS), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Université Côte d'Azur, CNRS, LPMC, France, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA), Département de Physique Théorique, University of Geneva [Switzerland], Laboratoire de physique de la matière condensée (LPMC), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS), and Université de Genève = University of Geneva (UNIGE)

Subjects
Quantum point contact, FOS: Physical sciences, Physics::Optics, 02 engineering and technology, Electron, 01 natural sciences, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], Quantum mechanics, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), 0103 physical sciences, Astronomical interferometer, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, Quantum, Spin-½, [PHYS]Physics [physics], Physics, Quantum Physics, Mesoscopic physics, Condensed Matter - Mesoscale and Nanoscale Physics, Degenerate energy levels, Astrophysics::Instrumentation and Methods for Astrophysics, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Interferometry, PACS numbers: 72.70.+m, 73.23.-b, 73.63.-b, Quantum Physics (quant-ph), 0210 nano-technology
Abstract

The distribution of electron waiting times is useful to characterize quantum transport in mesoscopic structures. Here we consider a generic quantum-coherent conductor consisting of a mesoscopic scatterer in a two-terminal setup. We extend earlier results for single-channel conductors to setups with several (possibly spin-degenerate) conduction channels and we discuss the effect of a finite electronic temperature. We present detailed investigations of the electron waiting times in a quantum point contact as well as in two mesoscopic interferometers with energy-dependent transmissions: a Fabry-P\'erot interferometer and a Mach-Zehnder interferometer. We show that the waiting time distributions allow us to determine characteristic features of the scatterers, for instance the number of resonant levels in the Fabry-P\'erot interferometer that contribute to the electronic transport., Comment: 13 pages, 11 figures

Published
2014

7. Inside-outside duality for planar billiards: A numerical study

Author

Jean-Pierre Eckmann, Barbara Dietz, Claude-Alain Pillet, Uzy Smilansky, Iddo Ussishkin, Centre de Physique Théorique - UMR 6207 (CPT), Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN)-Université de Provence - Aix-Marseille 1-Université de la Méditerranée - Aix-Marseille 2, Centre de Physique Théorique - UMR 7332 (CPT), Aix Marseille Université (AMU)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Département de Physique Théorique, University of Geneva [Switzerland], Section de mathématiques [Genève], Université de Genève (UNIGE), Laboratoire de Spectrométrie Physique (LSP), Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Department of Physics of Complex Systems, Weizmann Institute of Science [Rehovot, Israël], Université de la Méditerranée - Aix-Marseille 2-Université de Provence - Aix-Marseille 1-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), and Université de Genève = University of Geneva (UNIGE)

Subjects
quantum billiards, [PHYS.MPHY]Physics [physics]/Mathematical Physics [math-ph], FOS: Physical sciences, Duality (optimization), ddc:500.2, 01 natural sciences, 010305 fluids & plasmas, [MATH.MATH-MP]Mathematics [math]/Mathematical Physics [math-ph], 0103 physical sciences, [MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP], ddc:510, Connection (algebraic framework), 010306 general physics, Eigenvalues and eigenvectors, Physics, scattering theory, Scattering, Mathematics::Spectral Theory, Eigenfunction, Nonlinear Sciences - Chaotic Dynamics, Classical mechanics, Scattering theory, Chaotic Dynamics (nlin.CD), Dynamical billiards, inside-outside duality, Laplace operator, [MATH.MATH-SP]Mathematics [math]/Spectral Theory [math.SP]
Abstract

This paper reports the results of extensive numerical studies related to spectral properties of the Laplacian and the scattering matrix for planar domains (called billiards). There is a close connection between eigenvalues of the billiard Laplacian and the scattering phases, basically that every energy at which a scattering phase is $2\pi$ corresponds to an eigenenergy of the Laplacian. Interesting phenomena appear when the shape of the domain does not allow an extension of the eigenfunction to the exterior. In this paper these phenomena are studied and illustrated from several points of view., Comment: uuencoded tar-compressed (using uufiles) postscript file, 15 pages

Published
1995

8. Dynamical Coulomb Blockade Observed in Nanosized Electrical Contacts

Author

Konrad H. Mueller, François Patthey, Christophe Brun, I-Po Hong, Christian Flindt, Wolf-Dieter Schneider, Institut des Nanosciences de Paris (INSP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Département de Physique Théorique, Université de Genève = University of Geneva (UNIGE), and University of Geneva [Switzerland]

Subjects
Materials science, Scanning tunneling spectroscopy, FOS: Physical sciences, General Physics and Astronomy, Growth, 02 engineering and technology, Environment, 01 natural sciences, Charge, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), 0103 physical sciences, Quantum Size, Electronics, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, Pb, Spectroscopy, Quantum tunnelling, Condensed Matter - Mesoscale and Nanoscale Physics, Condensed matter physics, Temperature, Coulomb blockade, Conductance, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 021001 nanoscience & nanotechnology, Electrical contacts, Si(111), 3. Good health, Characterization (materials science), Surface, Tunnel-Junctions, 0210 nano-technology, Contact area
Abstract

Electrical contacts between nano-engineered systems are expected to constitute the basic building blocks of future nano-scale electronics. However, the accurate characterization and understanding of electrical contacts at the nano-scale is an experimentally challenging task. Here we employ low-temperature scanning tunneling spectroscopy to investigate the conductance of individual nano-contacts formed between flat Pb islands and their supporting substrates. We observe a suppression of the differential tunnel conductance at small bias voltages due to dynamical Coulomb blockade effects. The differential conductance spectra allow us to determine the capacitances and resistances of the electrical contacts which depend systematically on the island--substrate contact area. Calculations based on the theory of environmentally assisted tunneling agree well with the measurements., 5 pages, 3 figures, to appear in PRL

Published
2012

9. Evidence for Room-Temperature Multiferroicity in a Compound with a Giant Axial Ratio

Author

Abdelmadjid Anane, Laurent Bellaiche, Andrei Rogalev, Agnès Barthélémy, Grégorie Geneste, F. Wilhelm, Vincent Cros, Bertrand Dupé, Brahim Dkhil, Frédéric Petroff, Karim Bouzehouane, Sylvain Petit, Richard Mattana, Sergey Lisenkov, Eric Jacquet, Hélène Béa, Bénédicte Warot-Fonrose, Stéphane Fusil, Manuel Bibes, Inna Ponomareva, Unité mixte de physique CNRS/Thales (UMPhy CNRS/THALES), THALES [France]-Centre National de la Recherche Scientifique (CNRS), Département de Physique de la Matière Condensée (DPMC), Université de Genève = University of Geneva (UNIGE), Laboratoire Structures, Propriétés et Modélisation des solides (SPMS), Institut de Chimie du CNRS (INC)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), University of Arkansas [Fayetteville], Université d'Évry-Val-d'Essonne (UEVE), Centre d'élaboration de matériaux et d'études structurales (CEMES), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université 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), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), European Synchrotron Radiation Facility (ESRF), Laboratoire Léon Brillouin (LLB - UMR 12), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), THALES-Centre National de la Recherche Scientifique (CNRS), Université de Genève (UNIGE), 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), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay

Subjects
Theoretical prediction, Materials science, Epitaxial stabilization, General Physics and Astronomy, Monoclinic phase, 02 engineering and technology, Multiferroic, Epitaxy, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, Switchable polarization, Nuclear magnetic resonance, Polarization, 0103 physical sciences, Strain effect, Axial ratio, Antiferrodistortive, Multiferroics, 010306 general physics, Room temperature, Ferroelectric materials, Condensed matter physics, Multiferroic materials, Magnetic compounds, 021001 nanoscience & nanotechnology, Polarization (waves), Ferroelectricity, Unit cells, Polar, 0210 nano-technology, Monoclinic crystal system
Abstract

In the search for multiferroic materials magnetic compounds with a strongly elongated unit-cell (large axial ratio c/a) have been scrutinized intensely. However, none was hitherto proven to have a switchable polarization, an essential feature of ferroelectrics. Here, we provide evidence for the epitaxial stabilization of a monoclinic phase of BiFeO3 with a giant axial ratio (c/a=1.23) that is both ferroelectric and magnetic at room temperature. Surprisingly, and in contrast with previous theoretical predictions, the polarization does not increase dramatically with c/a. We discuss our results in terms of the competition between polar and antiferrodistortive instabilities and give perspectives for engineering multiferroic phases. © 2009 The American Physical Society.

Published
2009

10. Temperature in Nonequilibrium Systems with Conserved Energy

Author

Michel Droz, Olivier Dauchot, Eric Bertin, Department of Theoretical Physics (DTP), Université de Genève = University of Geneva (UNIGE), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), department of theoretical physics, Department of Theoretical Physics (DTP GENEVA), University of Geneva [Switzerland], and Dauchot, Olivier

Subjects
Physics, Statistical Mechanics (cond-mat.stat-mech), FOS: Physical sciences, General Physics and Astronomy, Non-equilibrium thermodynamics, Inverse temperature, Statistical mechanics, Numerical renormalization group, 01 natural sciences, 010305 fluids & plasmas, [PHYS.COND.CM-SM] Physics [physics]/Condensed Matter [cond-mat]/Statistical Mechanics [cond-mat.stat-mech], Microcanonical ensemble, Lattice (order), 0103 physical sciences, Statistical physics, [PHYS.COND.CM-SM]Physics [physics]/Condensed Matter [cond-mat]/Statistical Mechanics [cond-mat.stat-mech], 010306 general physics, Condensed Matter - Statistical Mechanics
Abstract

We study a class of nonequilibrium lattice models which describe local redistributions of a globally conserved energy. A particular subclass can be solved analytically, allowing to define a temperature T_{th} along the same lines as in the equilibrium microcanonical ensemble. The fluctuation-dissipation relation is explicitely found to be linear, but its slope differs from the inverse temperature T_{th}^{-1}. A numerical renormalization group procedure suggests that, at a coarse-grained level, all models behave similarly, leading to a two-parameter description of their macroscopic properties., 4 pages, 1 figure, final version

Published
2004

11. Width distribution of contact lines on a disordered substrate

Author

Alberto Rosso, Sébastien Moulinet, Werner Krauth, Etienne Rolley, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Département de Physique de la Matière Condensée (DPMC), Université de Genève = University of Geneva (UNIGE), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), and Université de Genève (UNIGE)

Subjects
Condensed matter physics, Distribution (number theory), Contact line, FOS: Physical sciences, Disordered Systems and Neural Networks (cond-mat.dis-nn), Substrate (electronics), Surface finish, Condensed Matter - Disordered Systems and Neural Networks, 01 natural sciences, 64.60.-i, 02.70.Tt, 83.60.Uv, 010305 fluids & plasmas, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0103 physical sciences, Boundary value problem, 010306 general physics, Mathematics
Abstract

We have studied the roughness of a contact line of a liquid meniscus on a disordered substrate by measuring its width distribution. The comparison between the measured width distribution and the width distribution calculated in previous works, extended here to the case of open boundary conditions, confirms that the Joanny-de Gennes model is not sufficient to describe the dynamics of contact lines at the depinning threshold. This conclusion is in agreement with recent measurements which determine the roughness exponent by extrapolation to large system sizes., 4 pages, 3 figures

Published
2004

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