arXiv subjects

Vladislav Korostelev

Publications and source records attributed to Vladislav Korostelev.

3 recordsLinked to original sources

arXiv2026

Electronic-Structure Correlations Governing Superconductivity in Nb-Based High-Entropy Alloys

Superconducting high-entropy alloys have recently emerged as a new platform for exploring superconductivity in highly disordered metallic systems and may offer advantages for applications requiring mechanical robustness and tolerance to extreme environments. Yet the mechanisms that govern their superconductivity, particularly the roles of lattice distortion and complex local order, both inherent to high-entropy alloys, remain unclear. The conventional valence-electron-concentration rule fails to reliably predict superconducting behavior, motivating a correlation analysis that links performance to electronic structure and lattice disorder. Here, we study a systematic series of niobium-based body-centered-cubic high-entropy alloys, from binary to quinary compositions, designed to investigate the electronic and structural effects and identify the dominant factors controlling superconductivity. Our experimental results reveal that the superconducting critical properties evolve non-monotonically with alloy complexity. Interestingly, alloys with greater lattice distortion can still achieve higher critical temperature and upper critical field. These observations are corroborated by first-principles and Eliashberg analyses, which identify the position of the niobium d-band relative to the Fermi level as the primary driver of electron-phonon coupling, critical temperature, and upper critical field, with lattice distortion serving as a secondary modifier that generally weakens coupling. We consolidate these findings into a detailed correlation map linking superconducting properties to electronic-structure fingerprints and vibrational signatures, establishing a mechanism-informed design strategy for superconducting high-entropy alloys with enhanced critical temperature and field.

cond-mat.supr-con↗

arXiv2026

Hydrogen in Brownmillerite Perovskites: First-Principles Insights into Energetics and Induced Electronic-Magnetic Changes

Hydrogen uptake in brownmillerite perovskites A2B2O5 offers an (electro)chemically accessible route to tune functional properties, but mechanistic understanding and design rules for hydrogen-responsive oxides remain limited. Here we employ density functional theory (DFT) to quantify how H absorption affects electronic structure, magnetic exchange, and anisotropy in representative Sr2Fe2O5 and Sr2Co2O5 oxides. We find that hydrogenation introduces a localized electron that stabilizes near the proton, with B-site-dependent preference. The resulting lattice distortions and redistribution of charge density modify exchange coupling and cant the Neel vector, giving rise to weak ferromagnetism. We also show that absorption energies are highly sensitive to proton-electron arrangements and magnetic order, varying by up to 1 eV across different settings. This sensitivity demands consistent treatment of charge localization and spin states, together with careful choice of computational parameters. Extending to a variety of experimentally reported A2B2O5 compositions, we identify candidates with favorable H uptake and uncover a trend linking more favorable absorption to a higher B-site d-electron count. We also demonstrate that the preferred proton absorption site in these materials is governed by local O-O separations and lattice flexibility, which describe the ability of the framework to accommodate proton-induced distortions. Finally, benchmarks of universal machine-learning interatomic potentials reveal uncertainties of about 1 eV for site-resolved absorption energies, motivating descriptor-based surrogate models and targeted DFT validation. Together, these results establish practical design rules for hydrogen-responsive oxides relevant to iono-electronic devices, sensors, and electrically tunable spin functionality.

cond-mat.mtrl-sci↗

arXiv2025

Anomalous spin-lattice coupling in a 2D antiferromagnetic semiconductor revealed by surface acoustic Rayleigh waves

Magnetic order in van der Waals magnets can strongly influence their lattice dynamics, yet how this interaction manifests across different phonon length scales remains unclear. Optical phonons probe bond-scale exchange modulation and short-range spin correlations, whereas long-wavelength acoustic modes couple to uniform strain fields and are sensitive to the renormalization of the macroscopic elastic tensor associated with long-range magnetic order. Experimentally accessing these low-energy acoustic excitations in low-dimensional crystals is challenging due to their low energies and the small lateral dimensions of exfoliated samples. Here, we employ angle-resolved Brillouin-Mandelstam scattering spectroscopy to investigate the surface acoustic phonon spectrum of exfoliated NiPS3 thin films across their antiferromagnetic transition temperature. Our results show a single Rayleigh surface mode whose phase velocity exhibits a pronounced 5.5% softening upon cooling through the Neel temperature. This anomaly reflects a giant magnetoelastic renormalization of the long-wavelength elastic constants triggered by the onset of zigzag antiferromagnetic order. First-principles calculations of the full elastic tensor, combined with continuum finite-element modelling of the NiPS3/SiO2/Si heterostructure, reproduce both the Rayleigh-wave dispersion and its magnetic-order-induced shift. The obtained results reveal how microscopic exchange interactions shape macroscopic mechanical properties in two-dimensional antiferromagnetic semiconductors, providing a basis for lattice-controlled magnetism and magnetically tunable phononic, magnonic, and strain-mediated spintronic device concepts.

cond-mat.mtrl-sci↗