Supercondutivity in SnSb with natural superlattice structure

TL;DR

This study demonstrates bulk superconductivity in polycrystalline SnSb with a natural superlattice structure, revealing a fully gapped, type-II superconductor with a Tc of 1.50 K, and compares it to related topological semimetals.

Contribution

First evidence of bulk superconductivity in a natural superlattice derived from a topological semimetal, expanding understanding of superconductivity in layered materials.

Findings

Superconducting transition temperature (Tc) is 1.50 K.

Zero resistivity transition occurs at 2.48 K.

Upper critical field is 520 Oe.

Abstract

We report the results of electrical resistivity, magnetic and thermodynamic measurements on polycrystalline SnSb, whose structure consists of stacks of Sb bilayers and Sn4Sb3 septuple layers along the c-axis. The material is found to be a weakly coupled, fully gapped, type-II superconductor with a bulk Tc of 1.50 K, while showing a zero resistivity transition at a significantly higher temperature of 2.48 K. The Sommerfeld coefficient and upper critical field, obtained from specific heat measurements, are 2.29 mJ/mol K and 520 Oe, respectively. Compositional inhomogeneity and strain effect at the grain boundaries are proposed as possible origins for the difference in resistive and bulk superconducting transitions.In addition, a comparison with the rock-salt structure SnAs superconductor is presented. Our results provide the first clear evidence of bulk superconductivity in a natural superlattice derived from a topological semimetal.