Elastic, electronic, thermodynamic and transport properties of XOsSi (X=Nb, Ta) superconductors: A first-principles exploration

TL;DR

This study uses first-principles calculations to explore the elastic, electronic, thermodynamic, transport, and superconducting properties of XOsSi (X=Nb, Ta) superconductors, revealing their stability, anisotropy, metallic nature, and weak superconducting coupling.

Contribution

First comprehensive calculation of elastic constants and moduli for XOsSi superconductors, highlighting their stability, anisotropy, and weak electron-phonon coupling.

Findings

XOsSi compounds are elastically stable and ductile.

Both compounds exhibit high elastic anisotropy.

They are weakly coupled superconductors with metallic band structures.

Abstract

A first-principles calculation has been performed to study elastic, electronic, thermodynamic, transport and superconducting properties of recently reported osmium based two superconductors, XOsSi (X=Nb, Ta). We have calculated elastic constants and elastic moduli of XOsSi for the first time. The calculated values of bulk, Youngs, shear moduli are reasonably larger than the average value obtained from the rule of mixtures of the constituents. NbOsSi and TaOsSi both compounds are found to be relatively hard material, elastically stable and ductile in nature. The obtained directional bulk modulus and shear anisotropic factors indicate that both compounds have high elastic anisotropy. The shear anisotropic factors show higher elastic anisotropy than the percentage anisotropy in these compounds. The Debye temperature and bulk modulus increases with pressure but decreases with temperature as usual for metals. The magnetic susceptibility of TaOsSi follow the Curie law but NaOsSi do not follow due to its delocalized magnetic moment and electronic specific heat slightly deviates from the linear relationship with temperature. The calculated band structures of XOsSi compounds show metallic nature. In both cases d-orbitals have the dominating contribution to the total density of states. The smaller electron-phonon coupling constant implies that XOsSi (X=Nb, Ta) are weakly coupled superconductors.