Single layer clathrane: A potential superconducting two-dimensional (2D) hydrogenated metal borocarbide

TL;DR

This paper introduces a new family of 2D hydrogenated metal borocarbide clathrane superconductors, demonstrating how strain and doping can enhance their superconducting transition temperature.

Contribution

It proposes a novel 2D clathrane structure derived from 3D parent compounds and explores how strain and doping influence their superconducting properties.

Findings

Hydrogen passivation stabilizes the 2D monolayers.

Strain engineering can increase  by up to 15.5 K.

Surface metal decoration and doping tune superconductivity.

Abstract

We propose a new family of two-dimensional (2D) metal-borocarbide clathrane superconductors, derived from three-dimensional (3D) MM$^\prime$B$_6$C$_6$ clathrates. First-principles calculations reveal that hydrogen passivation and surface metal decoration stabilize the M$_2$M$^\prime$B$_8$C$_8$H$_8$ monolayers. These 2D systems exhibit tunable superconductivity governed by hole concentration, structural anisotropy, and electron-phonon coupling. We find that in-plane anisotropy competes with superconductivity, reducing \tc\ despite favorable doping. Biaxial strain mitigates this anisotropy, enhances Fermi surface nesting, and increases \tc\ by an average of 15.5~K. For example, the \tc\ of Sr$_3$B$_8$C$_8$H$_8$ is predicted to increase from 11.3~K to 22.2~K with strain engineering. These findings identify 2D clathranes as promising, strain-tunable superconductors and highlight design principles for optimizing low-dimensional superconducting materials.