Superconductivity and topological behavior in gallenene

TL;DR

This paper demonstrates that gallenene, a 2D monolayer of gallium, is intrinsically superconducting with topological edge states, and shows that chemical functionalization can enhance its superconducting properties.

Contribution

It reveals that gallenene is a simple 2D superconductor with topological features and higher $T_c$ than bulk gallium, introducing new possibilities for 2D superconducting materials.

Findings

Gallenene exhibits intrinsic superconductivity with $T_c$ of 7-10 K.

Ga-100 gallenene has three-gap superconductivity, unlike buckled Ga-010.

Hydrogen functionalization induces multigap superconductivity with higher $T_c$.

Abstract

Among the large variety of two-dimensional (2D) materials discovered to date, elemental monolayers that host superconductivity are very rare. Using ab initio calculations we show that recently synthesized gallium monolayers, coined gallenene, are intrinsically superconducting through electron-phonon coupling. We reveal that Ga-100 gallenene, a planar monolayer isostructural with graphene, is the structurally simplest 2D superconductor to date, furthermore hosting topological edge states due to its honeycomb structure. Our anisotropic Eliashberg calculations show distinctly three-gap superconductivity in Ga-100, in contrast to the alternative buckled Ga-010 gallenene which presents a single anisotropic superconducting gap. Strikingly, the critical temperature ($T_c$) of gallenene is in the range of $7-10$ K, exceeding the $T_c$ of bulk gallium from which it is exfoliated. Finally we explore chemical functionalization of gallenene with hydrogen, and report induced multigap superconductivity with an enhanced $T_c$ in the resulting gallenane compound.