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

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.