Superconductivity in Tl_{0.6}Bi_{2}Te_{3} Derived from a Topological Insulator

TL;DR

This paper reports the discovery of bulk superconductivity in Tl_{0.6}Bi_{2}Te_{3}, a material derived from the topological insulator Bi2Te3, with high volume fraction and unconventional critical field behavior, suggesting potential topological superconductivity.

Contribution

It demonstrates superconductivity in Tl_{0.6}Bi_{2}Te_{3} derived from a topological insulator, highlighting its potential as a topological superconductor candidate.

Findings

Superconductivity with Tc of 2.28 K and 95% volume fraction.

Unconventional temperature dependence of the upper critical field B_{c2}.

Tl ions are incorporated but not intercalated, with unchanged crystal structure except for shorter c-lattice.

Abstract

Bulk superconductivity has been discovered in Tl_{0.6}Bi_{2}Te_{3}, which is derived from the topological insulator Bi2Te3. The superconducting volume fraction of up to 95% (determined from specific heat) with Tc of 2.28 K was observed. The carriers are p-type with the density of ~1.8 x 10^{20} cm^{-3}. Resistive transitions under magnetic fields point to an unconventional temperature dependence of the upper critical field B_{c2}. The crystal structure appears to be unchanged from Bi2Te3 with a shorter c-lattice parameter, which, together with the Rietveld analysis, suggests that Tl ions are incorporated but not intercalated. This material is an interesting candidate of a topological superconductor which may be realized by the strong spin-orbit coupling inherent to topological insulators.