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

摘要

Bulk superconductivity has been discovered in Tl_{0.6}Bi_{2}Te_{3}, which isderived from the topological insulator Bi2Te3. The superconducting volumefraction of up to 95% (determined from specific heat) with Tc of 2.28 K wasobserved. The carriers are p-type with the density of ~1.8 x 10^{20} cm^{-3}.Resistive transitions under magnetic fields point to an unconventionaltemperature dependence of the upper critical field B_{c2}. The crystalstructure appears to be unchanged from Bi2Te3 with a shorter c-latticeparameter, which, together with the Rietveld analysis, suggests that Tl ionsare incorporated but not intercalated. This material is an interestingcandidate of a topological superconductor which may be realized by the strongspin-orbit coupling inherent to topological insulators.