Superconductivity in Few-Layer Stanene

TL;DR

This study uncovers superconductivity in few-layer stanene, revealing layer-dependent properties and potential for topological superconductivity, with implications for quantum physics and material engineering.

Contribution

It demonstrates superconductivity in few-layer stanene, a phenomenon not observed in bulk tin, and explores the transition from single-band to two-band superconductivity via substrate engineering.

Findings

Superconductivity observed in bilayer stanene grown on PbTe.

Transition from single-band to two-band superconductivity with increased T_c.

Band structure analysis indicates the presence of topologically nontrivial states.

Abstract

A single atomic slice of {\alpha}-tin-stanene-has been predicted to host quantum spin Hall effect at room temperature, offering an ideal platform to study low-dimensional and topological physics. While recent research has intensively focused on monolayer stanene, the quantum size effect in few-layer stanene could profoundly change material properties, but remains unexplored. By exploring the layer degree of freedom, we unexpectedly discover superconductivity in few-layer stanene down to a bilayer grown on PbTe, while bulk {\alpha}-tin is not superconductive. Through substrate engineering, we further realize a transition from a single-band to a two-band superconductor with a doubling of the transition temperature. In-situ angle resolved photoemission spectroscopy (ARPES) together with first-principles calculations elucidate the corresponding band structure. Interestingly, the theory also indicates the existence of a topologically nontrivial band. Our experimental findings open up novel strategies for constructing two-dimensional topological superconductors.