A5052439473- High-pressure geophysics and materials
- Quantum, superfluid, helium dynamics
- Advanced Chemical Physics Studies
- Superconductivity in MgB2 and Alloys
- Physics of Superconductivity and Magnetism
- Topological Materials and Phenomena
- Rare-earth and actinide compounds
- 2D Materials and Applications
- Organic and Molecular Conductors Research
- Boron and Carbon Nanomaterials Research
- Advanced Condensed Matter Physics
- Superconducting Materials and Applications
- Iron-based superconductors research
- Graphene research and applications
- Hydrogen Storage and Materials
- Thermal properties of materials
- Machine Learning in Materials Science
- Inorganic Fluorides and Related Compounds
- Inorganic Chemistry and Materials
- Electronic and Structural Properties of Oxides
- Chalcogenide Semiconductor Thin Films
- Solid-state spectroscopy and crystallography
- Thermal Radiation and Cooling Technologies
- Perovskite Materials and Applications
- Diamond and Carbon-based Materials Research
Donostia International Physics Center
2016-2025
University of the Basque Country
2016-2025
Material Physics Center
2011-2025
Ayuntamiento de San Sebastián
2024
Institut de minéralogie, de physique des matériaux et de cosmochimie
2013-2017
Ikerbasque
2013-2015
Université Paris Cité
2015
Institut de Recherche pour le Développement
2015
Centre National de la Recherche Scientifique
2014-2015
Sorbonne Université
2014-2015
We use first-principles calculations to study structural, vibrational, and superconducting properties of H_{2}S at pressures P≥200 GPa. The inclusion zero-point energy leads two different possible dissociations H2S, namely 3H2S→2H3S+S 5H2S→3H3S+HS2, where both H3S HS2 are metallic. For H3S, we perform nonperturbative anharmonic effects within the self-consistent harmonic approximation show that strongly overestimates electron-phonon interaction (λ≈2.64 200 GPa) Tc. Anharmonicity hardens H─S...
Harmonic calculations based on density-functional theory are generally the method of choice for description phonon spectra metals and insulators. The inclusion anharmonic effects is, however, delicate as it relies perturbation requiring a considerable amount computer time, fast increasing with cell size. Furthermore, breaks down when harmonic solution is dynamically unstable or correction energies larger than frequencies themselves. We present here stochastic implementation self-consistent...
Pressure-stabilized hydrides are a new rapidly growing class of high-temperature superconductors which is believed to be described within the conventional phonon-mediated mechanism coupling. Here we report synthesis yttrium hexahydride Im3m-YH$_6$ that demonstrates superconducting transition with T$_c$ = 224 K at 166 GPa, much lower than theoretically predicted (>270 K). The measured upper critical magnetic field B$_c$$_2$(0) YH$_6$ was found 116-158 T, 2-2.5 times larger calculated value. A...
The measurement of superconductivity at above 200K in compressed samples hydrogen sulfide and lanthanum hydride 250K is reinvigorating the search for conventional high temperature superconductors. At same time it exposes a fascinating interplay between theory, computation experiment. Conventional well understood, theoretical tools are available accurate predictions superconducting critical temperature. These depend on knowing microscopic structure material under consideration, can now be...
Palladium hydrides display the largest isotope effect anomaly known in literature. Replacement of hydrogen with heavier isotopes leads to higher superconducting temperatures, a behavior inconsistent harmonic theory. Solving self-consistent approximation by stochastic approach, we obtain anharmonic free energy, thermal expansion, and properties fully ab initio. We find that phonon spectra are strongly renormalized anharmonicity far beyond perturbative regime. Superconductivity is mediated,...
When electric conductors differ from their mirror image, unusual chiral transport coefficients appear that are forbidden in achiral metals, such as a non-linear response known electronic magneto-chiral anisotropy (eMChA). While signatures by symmetry allowed many without center of inversion, it reaches appreciable levels only rare cases when an exceptionally strong coupling to the itinerant electrons is present. So far, observations have been limited materials which atomic positions strongly...
Abstract The primary challenge in the field of high-temperature superconductivity hydrides is to achieve a superconducting state at ambient pressure rather than extreme pressures that have been required experiments so far. Here, we propose family compounds, composition Mg 2 XH 6 with X = Rh, Ir, Pd, or Pt, achieves this goal. These materials were identified by scrutinizing more million compounds using machine-learning accelerated high-throughput workflow. We predict their transition...
Abstract A machine‐learning‐assisted approach is employed to search for superconducting hydrides under ambient pressure within an extensive dataset comprising over 150 000 compounds. The investigation yields ≈50 systems with transition temperatures surpassing 20 K, and some even reaching above 70 K. These compounds have very different crystal structures, dimensionality, chemical composition, stoichiometry, arrangement of the hydrogens. Interestingly, most these display slight thermodynamic...
The self-consistent harmonic approximation is an effective theory to calculate the free energy of systems with strongly anharmonic atomic vibrations, and its stochastic implementation has proved be efficient method study, from first-principles, properties solids. as a function average positions (centroids) can used study quantum or thermal lattice instability. In particular centroids are order parameters in second-order structural phase transitions such as, e.g., charge-density-waves...
Hydrogen sulfides have recently received a great deal of interest due to the record high superconducting temperatures up 203 K observed on strong compression dihydrogen sulfide (H2S). A joint theoretical and experimental study is presented in which decomposition products structures compressed H2S are characterized, their properties calculated. In addition experimentally known H3S phases, our first-principles structure searches identified several energetically competitive stoichiometries that...
Abstract The biaxial van der Waals semiconductor α‐phase molybdenum trioxide (α‐MoO 3 ) has recently received significant attention due to its ability support highly anisotropic phonon polaritons (PhPs)—infrared (IR) light coupled lattice vibrations—offering an unprecedented platform for controlling the flow of energy at nanoscale. However, fully exploit extraordinary IR response this material, accurate dielectric function is required. Here, α‐MoO reported by modeling far‐field polarized...
Since 2014 the layered semiconductor SnSe in high-temperature Cmcm phase is known to be most efficient intrinsic thermoelectric material. Making use of first-principles calculations we show that its vibrational and thermal transport properties are determined by huge nonperturbative anharmonic effects. We transition from low-symmetry Pnma a second-order driven collapse zone border phonon, whose frequency vanishes at temperature. Our spectral function in-plane modes strongly anomalous with...
The interplay between charge density wave (CDW) order and superconductivity has attracted much attention. This is the central issue of along standing debate in simple transition metal dichalcogenides without strong electronic correlations, such as 2H-NbSe$\_2$, which twosuch phases coexist. importance anisotropic electron-phonon interaction been recently highlighted from both theoretical experimental point view, explains some key features formation CDW this system. On other hand, aspects,...
We present first-principles calculations of metallic atomic hydrogen in the 400-600 GPa pressure range a tetragonal structure with space group $I4_1/amd$, which is predicted to be its first phase. Our show band close free-electron-like limit due high electronic kinetic energy induced by pressure. Bands are properly described even independent electron approximation fully neglecting electron-electron interaction. Linear-response harmonic dynamically stable phonon spectrum marked Kohn...
The self-consisted harmonic approximation (SCHA) allows the computation of free energy anharmonic crystals considering both quantum and thermal fluctuations. Recently, a stochastic implementation SCHA has been developed, tailored for applications that use total forces computed from first principles. In this work, we extend applicability to complex with many degrees freedom, optimisation lattice vectors atomic positions. To goal, provide an expression evaluation pressure stress tensor within...
Abstract By analyzing structural and electronic properties of more than a hundred predicted hydrogen-based superconductors, we determine that the capacity creating an bonding network between localized units is key to enhance critical temperature in superconductors. We define magnitude named as networking value, which correlates with better any other descriptor analyzed thus far. classifying studied compounds according their nature, observe such correlation bonding-type independent, showing...
Abstract Electromagnetic field confinement is crucial for nanophotonic technologies, since it allows enhancing light–matter interactions, thus enabling light manipulation in deep sub‐wavelength scales. In the terahertz (THz) spectral range, radiation conventionally achieved with specially designed metallic structures—such as antennas or nanoslits—with large footprints due to rather long wavelengths of THz radiation. this context, phonon polaritons—light coupled lattice vibrations—in van der...
The recent report of near-ambient conditions superconductivity in a nitrogen-doped lutetium hydride has inspired large number experimental studies with contradictory results. We model from first principles the physical properties possible parent structures reported superconductors, ${\mathrm{LuH}}_{2}$ and ${\mathrm{LuH}}_{3}$. show that only phonon band structure ${\mathrm{LuH}}_{3}$ can explain Raman spectra due to presence hydrogens at interstitial octahedral sites. However, this is...