Superconductivity by alloying the topological insulator SnBi2Te4

TL;DR

Alloying indium into SnBi2Te4 induces bulk superconductivity with topological surface states, making it a promising candidate for topological superconductivity research.

Contribution

This study demonstrates that alloying indium into SnBi2Te4 induces superconductivity while preserving topological surface states, a novel combination in this material family.

Findings

Superconductivity with Tc up to 1.85 K confirmed by multiple measurements.

Superconducting gap estimated near 0.25 meV, consistent with weak coupling BCS theory.

Topological surface states verified by photoemission spectroscopy.

Abstract

Alloying indium into the topological insulator Sn1-xInxBi2Te4 induces bulk superconductivity with critical temperatures Tc up to 1.85 K and upper critical fields up to about 14 kOe. This is confirmed by electrical resistivity, heat capacity, and magnetic susceptibility measurements. The heat capacity shows a discontinuity at Tc and temperature dependence below Tc consistent with weak coupling BCS theory, and suggests a superconducting gap near 0.25 meV. The superconductivity is type-II and the topological surface states have been verified by photoemission. A simple picture suggests analogies with the isostructural magnetic topological insulator MnBi2Te4, in which a natural heterostructure hosts complementary properties on different sublattices, and motivates new interest in this large family of compounds. The existence of both topological surface states and superconductivity in Sn1-xInxBi2Te4 identifies these materials as promising candidates for the study of topological superconductivity.