Theoretical analysis of spin-orbit coupling-weakened superconductivity in Bi-rich Ba 2 Bi 3 compound

Abstract

We have explored the structural, electronic, elastic, mechanical, lattice dynamical, and electron-phonon interaction properties of the body-centered orthorhombic Ba 2 Bi 3 compound by means of the density-functional theory and the densityfunctional perturbative theory, with the Perdew-Burke-Ernzerhof generalized gradient approximation of the exchange-correlation functional, within its spin-orbit coupling (SOC) version. The effects of SOC on elastic constants and elastic moduli are presented and discussed in detail. A comparison of non-SOC and SOC electronic and phonon structures shows that this coupling make moderate effects on them. Furthermore, the influence of this coupling on the strength of electron-phonon coupling (λ) is also examined. For the studied compound, we observe that the value of λ decreases from 1.3192 to 0.8835 by around % 33 with the inclusion of SOC. A detailed analysis our non-SOC and SOC results reveals that the origin of the SOC-induced diminishment of λ mainly lies in a decrease in the electron-phonon coupling matrix elements rather SOC-induced moderate modifications in its electronic and phonon structures. However, we have to mention that the SOC-weakened superconductivity in Bi-rich Ba 2 Bi 3 compound improves the agreement with experiment.