First-principles Calculation of Superconductivity in Hole-doped LiBC: $T_c=65$ K

TL;DR

This study uses first-principles calculations to explore superconductivity in hole-doped LiBC, predicting a transition temperature of about 65 K driven by electron-phonon interactions.

Contribution

It provides detailed first-principles analysis of LiBC's superconducting properties, highlighting the relationship between doping level, Fermi surface nesting, and electron-phonon coupling.

Findings

Electron-phonon coupling parameter $mbda$ increases with decreasing $x$.

Maximum $mbda$ of 1.4 at $x=0.125$.

Predicted $T_c$ of approximately 65 K at $x=0.5$.

Abstract

The lattice dynamical properties of Li$_x$BC are calculated for several values of $x$ using density functional perturbation theory. We find that the electron-phonon coupling parameter $\lambda$ increases monotonically with decreasing $x$ to a maximum value of 1.4 for $x=0.125$ owing to the increasing radius of multiply-nested Fermi surface cylinders. The B-C bond-stretching phonon modes have frequencies which are 28% higher than the equivalent modes in MgB$_2$. This combination results in a $T_c$ of about 65 K for $x=0.5$.