Superconductivity in intercalated buckled two-dimensional materials: KGe$_2$

TL;DR

This paper predicts superconductivity in potassium-intercalated germanene (KGe2) with a transition temperature around 11-12 K, highlighting the role of buckled structure and electron-phonon interactions.

Contribution

It demonstrates the potential for superconductivity in intercalated germanene, a novel 2D material, and explores how strain affects its superconducting properties.

Findings

Superconductivity in KGe2 with Tc ~11 K

Strain increases Tc to ~12 K

Buckled structure enhances electron-phonon coupling

Abstract

Germanene has emerged as a novel two-dimensional material with various interesting properties and applications. Here we report the possibility of superconductivity in a stable potassium intercalated germanene compound, KGe$_2$, with a transition temperature $T_c \sim 11$ K, and an electron-phonon coupling of 1.9. Applying a 5\% tensile strain, which reduces the buckling height by 4.5\%, leads to the reduction of the electron-phonon coupling by 11\% and a slight increase in $T_c \sim 12$ K. That is, strong electron-phonon coupling results from the buckled structure of the germanene layers. Despite being an intercalated van der Waals material similar to intercalated graphite superconductors, it does not possess an occupied interlayer state.