A5013431317- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Ferroelectric and Piezoelectric Materials
- Magnetic properties of thin films
- Iron-based superconductors research
- Superconducting and THz Device Technology
- Magnetic Properties of Alloys
- Theoretical and Computational Physics
- Superconducting Materials and Applications
- Rare-earth and actinide compounds
- Quantum and electron transport phenomena
- Dielectric properties of ceramics
- Advanced Battery Materials and Technologies
- Superconductivity in MgB2 and Alloys
- Dielectric materials and actuators
- High-pressure geophysics and materials
- Layered Double Hydroxides Synthesis and Applications
- Electronic and Structural Properties of Oxides
- Advanced Frequency and Time Standards
- Advanced Memory and Neural Computing
- Polyoxometalates: Synthesis and Applications
- Crystallization and Solubility Studies
- Metallic Glasses and Amorphous Alloys
- Magneto-Optical Properties and Applications
Université Paris Sciences et Lettres
2016-2025
Sorbonne Université
2015-2025
Centre National de la Recherche Scientifique
2015-2025
ESPCI Paris
2015-2025
Laboratoire de Physique et d’Étude des Matériaux
2015-2025
ParisTech
2012-2017
University of Puerto Rico at Carolina
2010
École Normale Supérieure - PSL
1993-2003
Laboratoire de Chimie et Physique Quantiques
2003
Laboratoire Albert Fert
1999
Abstract The charge compensation mechanisms that occur when Li + substitutes a 2+ element in superionic conductor (MgCoNiCuZn)O high‐entropy oxide have been studied using combination of thermogravimetric analysis and X‐ray photoemission spectroscopy. Depending on the concentration compound, involves first partial oxidation Co into 3+ for low fraction , then both cobalt formation oxygen vacancies large .
Over the past few years, ionic conductors have gained a lot of attention because possibility implementing them in various applications such as supercapacitors, batteries or fuel cells, and resistive memories. Especially, layered two-dimensional (2D) crystals, h-BN, graphene oxide, MoSe2, been shown to provide unique properties originating from specific 2D confinement moving ions. Two important parameters are ion conductivity chemical stability over wide range operating conditions. In this...
A two-channel scenario for the conductivity of underdoped YBa 2Cu 3O (7-delta) is proposed. One single-particle excitations channel, which dominates in optimally doped material, whose resistivity linear as a function temperature. The other one gives contribution merges 3D Aslamazov-Larkin fluctuation at low temperature and obeys power law high temperature, depending on two superconductive parameters (T(c) zero coherence length xi(c0)) an energy scale Delta(*). This allows to address nature...
The microscopic nature of an insulating state in the vicinity a superconducting state, presence disorder, is hotly debated question. While simplest scenario proposes that Coulomb interactions destroy Cooper pairs at transition, leading to localization single electrons, alternate possibility supported by experimental observations suggests instead directly localize. question homogeneity, granularity, or possibly glassiness material on verge this transition intimately related fundamental issue....
The two-dimensional nature of the Rb 2 Ti O 5 perovskite structure is highlighted, as crystal naturally cleaves along (001) planes in humid environments and a well-ordered network adsorbed water molecules forms on surface.
In this article we describe the effect of ion irradiation on high-Tc superconductor thin film and its interest for fabrication Josephson junctions. particular, show that these alternative techniques allow to go beyond most limitations encountered in standard junction methods, both case fundamental technological purposes. Two different geometries are presented: a planar one using single mesa defined trilayer structure.
The stable forms of palladium hydrides up to 100GPa were investigated using the direct reaction with hydrogen (deuterium) in a laser-heated diamond anvil cell. structure and volume PdH(D)x measured synchrotron x-ray diffraction. Pd atoms remain on fcc lattice. stoichiometry hydride is inferred from expansion due solubility No evidence for ratio greater than 1 observed both isotopes. An inverse isotope effect formation enthalpy stoichiometric disclosed by measuring equilibrium pressure PdH...
We present here high-precision magnetisation measurements in polycrystalline YBa2Cu3Ox samples, with oxygen content ranging from x=6.19 to x=7.00. By analysing the temperature derivative of susceptibility, we found underdoped superconducting samples a singular point at corresponding Tmag, below which polarised neutrons experiments have evidenced symmetry breaking. believe that this is thermodynamic indication for existence phase transition pseudogap state YBa2Cu3Ox.
Abstract Solid 4 He may acquire superfluid characteristics due to the frustration of solid phase at grain boundaries. Here, introducing a negative- U generalized Hubbard model and coarse-grained semiclassical pseudospin model, we show that an analogous effect occurs in systems with competition among charge-density-waves (CDW) superconductivity presence disorder, as cuprate or dichalcogenide superconductors. The CDW breaks apart domains topologically protected filamentary interfaces. Our...
From systematic analysis of the high pulsed magnetic field resistance data La$_{2-x}$Sr$_x$CuO$_{4}$ thin films, we extract an experimental phase diagram for several doping values ranging from very underdoped to overdoped regimes. Our highlights a competition between charge density waves and superconductivity which is ubiquitous $x=0.08$ $x=0.19$ produces previously observed double step transition. When suppressed by strong field, resilient two specific ranges centered around respectively...
Electrical conductivity and high dielectric constant are in principle self-excluding, which makes the terms insulator usually synonymous. This is certainly true when electrical carriers electrons, but not necessarily a material where ions extremely mobile, electronic conduction negligible charge transfer at interface immaterial. Here we demonstrate perovskite-derived structure containing five-coordinated Ti atoms, colossal (up to $\mbox{10}^9$) together with very ionic...
In this report, we combine thermogravimetric analysis, X-ray diffraction, and infrared spectroscopy to investigate the chemical structural evolution upon exposure of alkali titanates Rb
The contribution of superconducting fluctuations to the conductivity, or paraconductivity, is studied in underdoped regime ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}\mathrm{Cu}{\mathrm{O}}_{4}$ cuprates. A perpendicular magnetic field up $50\phantom{\rule{0.3em}{0ex}}\mathrm{T}$ applied suppress superconductivity and obtain normal state resistivity, which then used calculate paraconductivity. Surprisingly enough, it consistent with a two-dimensional Aslamazov-Larkin Gaussian close...
Electron irradiation is investigated as a way to dope the topological insulator Bi${}_{2}$Te${}_{3}$. For this, $p$-type Bi${}_{2}$Te${}_{3}$ single crystals have been irradiated with 2.5 MeV electrons at room temperature and electrical measurements performed in situ well ex magnetic fields up 14 T. The defects created by act electron donors, allowing compensation of initial hole-type conductivity material conversion from $p$ $n$ type. changes carrier concentration are using Hall effect...
We developed a two-step process showing the way for sintering anisotropic nanostructured bulk ferromagnetic materials. A new reactor has been optimized allowing synthesis of several grams per batch nanopowders via polyol soft chemistry route. The feasibility scale-up successfully demonstrated Co80Ni20 nanowires and massic yield ∼97% was obtained. thus obtained show an average diameter ∼6 nm length ∼270 nm. bottom-up strategy allowed us to compact powder into system. used...
We reconsider transport experiments in strongly anisotropic high-${T}_{c}$ superconducting cuprates and we find that the universal Aslamazov-Larkin paraconductivity two dimensions is surprisingly robust, even underdoped regime below pseudogap crossover temperature ${T\phantom{\rule{0.1em}{0ex}}}^{*}$. also establish underlying normal-state resistivity region (almost) linear temperature, with all deviations being quantitatively accounted for by paraconductivity. The disappearance of ruled...
Recent results have demonstrated an exceptionally high permittivity in the range 200–330 K crystalline titanium oxide Rb 2 Ti O 5 . In this article, possibility of a structural transition giving rise to ferroelectricity is carefully inspected. particular, X-ray diffraction, high-resolution transmission electron microscopy and Raman spectroscopy are performed. The crystal structure shown remain invariant centrosymmetric at all temperatures between 90 450 K. stability C 2/ m confirmed by...
Nanowires with very different size, shape, morphology, and crystal symmetry can give rise to a wide ensemble of magnetic behaviors whose optimization determines their applications in nanomagnets. We present here an experimental work on the shape morphological dependence magnetization reversal mechanism weakly interacting Co80Ni20 hexagonal-close-packed nanowires. Non-agglomerated nanowires (with length L diameter d) controlled going from quasi perfect cylinders diabolos have been studied...