Three-gap superconductivity with $T_{c}$ above 80 K in hydrogenated 2D monolayer LiBC

TL;DR

This paper predicts high-temperature three-gap superconductivity above 80 K in hydrogenated 2D LiBC monolayers using first-principles calculations, with potential for practical applications due to the high critical temperature.

Contribution

It introduces a novel hydrogenation approach to induce superconductivity in LiBC monolayers and demonstrates the possibility of achieving $T_c$ above 80 K with strain tuning.

Findings

LiBCH and LiCBH monolayers exhibit $T_c$ around 82 K.

Three-gap superconductivity is confirmed in these monolayers.

Applying 3.5% tensile strain raises $T_c$ to 120 K.

Abstract

Although the metalization of semiconductor bulk LiBC has been experimentally achieved, various flaws, including the strong lattice distortion, the uncontrollability of phase transition under pressure, usually appear. In this work, based on the first-principles calculations, we propose a new way of hydrogenation to realize metalization. Using the fully anisotropic Migdal-Eliashberg theory, we investigate the superconducting behaviors in the stable monolayers LiBCH and LiCBH, in which C and B atoms are hydrogenated, respectively. Our findings indicate that the monolayers possess the high $T_{c}$ of 82.0 and 82.5 K, respectively, along with the interesting three-gap superconducting natures. The Fermi sheets showing the obvious three-region distribution characteristics and the abnormally strong electron-phonon coupling (EPC) are responsible for the high-$T_{c}$ three-gap superconductivity. Furthermore, the $T_{c}$ can be dramatically boosted up to 120.0 K under 3.5 \% tensile strain. To a great extent, the high $T_{c}$ is beyond the liquid nitrogen temperature ($77$ K), which is beneficial for the applications in future experiments. This study not only explores the superconducting properties of the monolayers LiBCH and LiCBH, but also offers practical insights into the search for high-$T_{c}$ superconductors.