Impact of spin-orbit coupling on the physical properties and superconductivity of Ir-rich superconductor Mg2Ir3Si: A first-principles investigation

Abstract

In this study, we elucidate the impact of spin-orbit coupling (SOC) on the physical properties and superconductivity of ternary Laves compound Mg2Ir3Si by performing full relativistic and scalar relativistic ab initio pseudopotential calculations. The consideration of SOC shifts the scalar relativistic bands in energy and changes degeneracy of the bands, but the elastic and mechanical properties are marginally afftected. SOC decreases the electron-phonon coupling strength λ by 11% (from 1.05 to 0.93) A critical assessment of phonon spectrum and Eliashberg spectral function reveals that the origin of the SOC-induced diminishment of λ lies both in slight hardening of some low-frequency phonon modes and in a decrease in the electron-phonon coupling matrix elements. As a consequence, the inclusion of SOC reduces the value of superconducting transition temperature from 7.64 K to 7.05 K, resulting in improved agreement with its recent experimental value of 7 K.