High-temperature phonon-mediated superconductivity in monolayer Mg2B4C2

TL;DR

This paper predicts a new 2D material, Mg2B4C2, exhibiting high-temperature superconductivity around 47-48 K due to strong electron-phonon coupling and topological states, potentially enabling topological superconductivity.

Contribution

Theoretical prediction of a stable 2D Mg2B4C2 material with high Tc and topological properties, expanding the family of superconductors with intrinsic topological features.

Findings

Predicted Tc of 47-48 K without external tuning

Presence of strong electron-phonon coupling and topological Dirac states

Material remains stable with increased thickness

Abstract

A new two-dimensional material { Mg2B4C2, belonging to the family of the conventional superconductor MgB2, is theoretically predicted to exhibit superconductivity with critical temperature Tc estimated in the 47-48 K range (predicted using the McMillian-Allen-Dynes formula) without any tuning of external parameters such as doping, strain, or substrate-induced effects. The origin of such a high intrinsic Tc is ascribed to the presence of strong electron-phonon coupling and topological Dirac states (which are absent in MgB2) yielding a large density of states at the Fermi level. This material also features a nontrivial electronic band topology exhibiting Dirac points, practically gapless Dirac nodal lines, and topological nontrivial edge states. Consequently, it is a potential candidate for realization of topological superconductivity in 2D. This system is obtained after replacing the chemically active boron layers in MgB2 by chemically inactive boron-carbon layers. Hence, the surfaces of this material are inert. Our calculations confirm the stability of 2D Mg2B4C2. We also find that the key features of this material remain essentially unchanged when its thickness is increased by modestly increasing the number of inner MgB2 layers.