Andreev reflection spectroscopy on SnAs single crystals

TL;DR

This study investigates the superconducting properties of SnAs single crystals using Andreev reflection spectroscopy, revealing weakly coupled BCS superconductivity and potential topologically protected states.

Contribution

First detailed spectroscopic analysis of SnAs superconductivity confirming BCS weak coupling behavior and exploring topological states.

Findings

Superconductivity in SnAs is consistent with BCS weak coupling theory.

SnAs exhibits a superconducting energy gap of approximately 0.7 meV.

Electronic bandstructure suggests possible topologically protected states.

Abstract

Binary compounds of SnT family(T= As, Sb, Te, S, Se, P) exhibit novel properties like superconductivity, topologically protected states etc. Some of these compounds crystallize in NaCl type structure or in layered structure, both of which are considered potentially important for high-temperature/unconventional superconductivity. It was previously shown that K-doped BaBiO$_3$ with NaCl type structure exhibits superconducting state below $\sim$ 30 K. SnAs has crystallographic configuration that is exactly similar to K-doped BaBiO$_3$ and this warrants for the investigation of superconductivity in this material. Previously it was reported that SnAs exhibits weakly coupled type I superconductivity with an energy gap of 0.7 meV. Recently, the electronic bandstructure calculations has hinted to the existence of possible topologically protected states in SnAs. This has motivated us to investigate the superconducting nature of SnAs using point contact Andreev reflection spectroscopy. Our investigation revealed that superconductivity in SnAs can be well explained within the BCS framework in the weak coupling limit.