A5027398903- Iron-based superconductors research
- Rare-earth and actinide compounds
- Advancements in Battery Materials
- Machine Learning in Materials Science
- Magnetic and transport properties of perovskites and related materials
- Physics of Superconductivity and Magnetism
- Thermal properties of materials
- Advanced Battery Materials and Technologies
- Intellectual Capital and Performance Analysis
- Corporate Taxation and Avoidance
- Advanced Thermoelectric Materials and Devices
- Electronic and Structural Properties of Oxides
- Inorganic Chemistry and Materials
- Advanced Condensed Matter Physics
- Superconductivity in MgB2 and Alloys
- Thermal Expansion and Ionic Conductivity
- Electron and X-Ray Spectroscopy Techniques
- Semiconductor materials and devices
- Heusler alloys: electronic and magnetic properties
- Graphene research and applications
- Magnetic Properties of Alloys
- Advanced Battery Technologies Research
- Advanced Chemical Physics Studies
- Computational Drug Discovery Methods
- Crystallography and molecular interactions
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2016-2024
Université Grenoble Alpes
2017-2024
CEA LITEN
2016-2024
CEA Grenoble
2017-2024
École Polytechnique
2012-2017
Centre de Physique Théorique
2012-2017
Centre de Physique Théorique
2012-2017
Université Paris-Saclay
2015-2017
Centre National de la Recherche Scientifique
2012-2017
Chinese Academy of Sciences
2012-2017
Computing vibrational free energies (Fvib) and entropies (Svib) has posed a long-standing challenge to the high-throughput ab initio investigation of finite temperature properties solids. Here, we use machine-learning techniques efficiently predict Fvib Svib crystalline compounds in Inorganic Crystal Structure Database. Using descriptors based simply on chemical formula using training set only 300 compounds, mean absolute errors less than 0.04 meV/K/atom (15 meV/atom) are achieved for...
Manufacturing materials with tailorable characteristics requires a detailed understanding of their properties as function temperature. A study the mechanical stability and thermal conductivity several hundred oxides fluorides at temperatures up to 1000 K is presented.
Machine learning (ML) is increasingly becoming a helpful tool in the search for novel functional compounds. Here we use classification via random forests to predict stability of half-Heusler (HH) compounds, using only experimentally reported compounds as training set. Cross-validation yields an excellent agreement between fraction classified stable and actual truly ICSD. The ML model then employed screen 71 178 different 1:1:1 compositions, yielding 481 likely candidates. predicted HH from...
We performed a high-energy resolution angle-resolved photoemission spectroscopy investigation of overdoped Ba${}_{0.1}$K${}_{0.9}$Fe${}_{2}$As${}_{2}$ with ${T}_{c}=9$ K. The Fermi surface topology this material is similar to that KFe${}_{2}$As${}_{2}$ and differs from slightly less doped Ba${}_{0.3}$K${}_{0.7}$Fe${}_{2}$As${}_{2}$, implying Lifshitz transition occurred between $x=0.7$ $x=0.9$. Albeit for vertical node found at the tip emerging off-$M$-centered pocket lobes, superconducting...
We investigate the temporal evolution of electronic states at bismuth (111) surface by means time- and angle-resolved photoelectron spectroscopy. The binding energy bulklike bands oscillates with frequency ${A}_{1g}$ phonon mode, whereas are insensitive to coherent displacement lattice. A strong dependence oscillation amplitude on wave vector is correctly reproduced ab initio calculations electron-phonon coupling. Besides these oscillations, all also display a photoinduced shift towards...
The empty perovskite ${\mathrm{ScF}}_{3}$ exhibits negative thermal expansion up to 1100 K. We demonstrate that ab initio calculations of temperature-dependent effective phonon spectra allow us quantitatively describe the behavior this compound and suppression expansion. Based on result, we predict an anomalous temperature dependence conductivity interpret it as a general feature class. Finally, comment fact at such high is beyond reach quasiharmonic approximation discuss based mode...
The performances of lithium-ion batteries depend on the capability electrode materials to exchange lithium ions and electrons faster reversibly. LiNiO2 is a promising candidate for achieving high voltage capacity. However, its industrialization hindered by surface bulk instabilities. These instabilities are due redox processes involving charge transfer between cations anions. Therefore, fundamental understanding based further experimental evidence required resolve cation anion from in...
Heat management in thermoelectric and power devices as well random access memories poses a grand challenge can make the difference between working an abandoned device design. Despite prevalence of dislocations all these technologies, modeling their thermal resistance is based on 50-year-old analytical approximations, whose simplicity was driven by practical limitations rather than physical insight. We introduce efficient ab initio approach Green's functions computed two-dimensional...
Understanding the Fermi surface and low-energy excitations of iron or cobalt pnictides is crucial for assessing electronic instabilities such as magnetic superconducting states. Here, we propose implement a new approach to compute properties correlated electron materials, taking into account both screened exchange beyond local density approximation dynamical correlations. The scheme allows us resolve puzzle ${\mathrm{BaCo}}_{2}{\mathrm{As}}_{2}$, which standard structure techniques predict...
Next-generation high-efficiency Li-ion batteries require an electrolyte that is both safe and thermally stable.
The structure and growth of the solid electrolyte interphase (SEI) region between an electrode is one most fundamental yet less well-understood phenomena in solid-state batteries. We present atomistic simulation SEI for currently promising electrolytes (Li6PS5Cl), based on ab initio-trained machine learning interatomic potentials, over 30,000 atoms during 10 ns, well beyond capabilities conventional molecular dynamics. This unveils a two-step mechanism: Li-argyrodite chemical reaction...
Comparative experimental and theoretical studies of an iron-based superconductor its cobalt-based nonsuperconducting cousin show that increased electronic band filling in the latter leads to much weakened correlations, indicating importance correlations superconductivity a mechanism for tuning them.
Electronic Coulomb correlations lead to characteristic signatures in the spectroscopy of transition metal pnictides and chalcogenides: quasi-particle renormalizations, lifetime effects or incoherent badly metallic behavior above relatively low coherence temperatures are measures many-body due local Hubbard Hund's couplings. We review compare results angle-resolved photoemission experiments (ARPES) combined density functional/dynamical mean-field theory (DFT+DMFT) calculations. emphasize...
We performed a high-resolution angle-resolved photoemission spectroscopy study on superconducting (SC) Tl$_{0.63}$K$_{0.37}$Fe$_{1.78}$Se$_2$ ($T_c=29$ K) in the whole Brillouin zone (BZ). In addition to nearly isotropic $\sim$ 8.2 meV 2-dimensional (2D) SC gap ($2\Delta/k_BT_c\sim7$) quasi-2D electron Fermi surfaces (FSs) located around M$(\pi,0,0)$-A$(\pi,0,\pi)$, we observe $\sim 6.2$ ($2\Delta/k_BT_c\sim5$) Z-centered FS that rules out any d-wave pairing symmetry and rather favors an...
Abstract The promise enabled by boron arsenide’s (BAs) high thermal conductivity ( κ ) in power electronics cannot be assessed without taking into account the reduction incurred when doping material. Using first principles calculations, we determine induced different group IV impurities BAs as a function of concentration and charge state. We unveil general trend, where neutral scatter phonons more strongly than charged ones. C B Ge As show far weakest phonon scattering retain values over...
Cubic boron arsenide (BAs) is a promising compound semiconductor for thermal management applications due to its high conductivity, exceeding 1000 W m–1 K–1 at room temperature in high-quality samples. However, the as-grown BAs crystals usually exhibit large variations and electronic transport properties. The origin of these has thus far been inconclusive. Here, we investigate effects impurities on electrical properties BAs. Time-of-flight secondary ion mass spectrometry electron probe...
The question of whether silica nanoparticles can enhance the ionic conductivity a polymer electrolyte above its crystallization temperature has remained unclear for two decades following first experiments on these systems. We use molecular dynamics simulations to decipher atomic-scale mechanisms affecting properties LiTFSI-poly(ethylene oxide) electrolytes upon addition nanoparticles. At any concentration, adding significantly decreases conductivity. Most this reduction be simply accounted...
We investigated the effects of X‐ray beam damage during photoelectron spectroscopy measurement on LiNiO 2 electrodes. The degree induced by lab‐based and synchrotron radiation has been compared between pristine cycled electrodes, highlighting role positive solid electrode–electrolyte interphase to protect surface from damage. possible steps avoid or at least reduce beam‐induced are outlined.
The determination of the effective Coulomb interactions to be used in low-energy Hamiltonians for materials with strong electronic correlations remains one bottlenecks parameter-free structure calculations. We propose and benchmark a scheme determining local charge-transfer oxides related compounds. Intershell between electrons correlated shell ligand orbitals are taken into account an manner, leading reduction on shell. Our resolves inconsistencies as obtained by standard methods wide range...
We calculate the strength of frequency-dependent on-site electronic interactions in iron pnictides LaFeAsO, ${\mathrm{BaFe}}_{2}{\mathrm{As}}_{2}, {\mathrm{BaRu}}_{2}{\mathrm{As}}_{2}$, and LiFeAs chalcogenide FeSe from first principles within constrained random phase approximation. discuss accuracy an atomiclike parametrization two-index density-density interaction matrices based on calculation optimal set three independent Slater integrals, assuming that angular part Fe $d$ localized...
We present the first application of a recently proposed electronic-structure scheme to transition metal oxides: screened exchange dynamical mean-field theory includes non-local beyond local density approximation and correlations standard theory. Our results for spectral function SrVO3 are in agreement with available experimental data, including photoemission spectroscopy thermodynamics. Finally, 3d0 compound SrTiO3 serves as test case illustrate how reduces band structure techniques weakly...
The effects of electron-electron correlations on the low-energy electronic structure and their relationship with unconventional superconductivity are central aspects in research iron-based pnictide superconductors. Here we use soft x-ray angle-resolved photoemission spectroscopy to study how evolve different chemically substituted iron pnictides. We find that intrinsically related effective filling correlated orbitals, rather than obtained by valence counting. Combined density functional...
Angle-resolved photoemission spectroscopy is used to study the scattering rates of charge carriers from hole pockets near $\mathrm{\ensuremath{\Gamma}}$ in iron-based high-${T}_{c}$ hole-doped superconductors ${\mathrm{K}}_{x}{\mathrm{Ba}}_{1\ensuremath{-}x}{\mathrm{Fe}}_{2}{\mathrm{As}}_{2}$, $x=0.4$, and ${\mathrm{K}}_{x}{\mathrm{Eu}}_{1\ensuremath{-}x}{\mathrm{Fe}}_{2}{\mathrm{As}}_{2}$, $x=0.55$, electron-doped compound...