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TT: Fachverband Tiefe Temperaturen

TT 6: Superconductivity: Properties and Electronic Structure

TT 6.1: Talk

Monday, March 7, 2016, 10:00–10:15, H19

Superconductivity in intercalated topological insulator Tl_xBi₂Te₃ — •zhiwei wang^1,2, alexey a. taskin^1,2, and yoichi ando^1,2 — ¹Institute of Physics II, University of Cologne, D-50937 Cologne, Germany — ²Institute of Scientic and Industrial Research, Osaka University, Osaka 567-0047, Japan

Bulk superconductivity has been discovered in Tl_xBi₂Te₃, which is derived from the topological insulator Bi₂Te₃ by intercalating Tl. The superconducting volume fraction of up to 95% (determined from specific heat) with T_c of 2.28 K is obtained for samples with x = 0.6, where the carriers are p-type with the density of ∼1.8 × 10²⁰ cm⁻³. The thermodynamic upper critical field B_c2 obtained from specific heat presents a conventional temperature dependence with the zero-temperature-limit value of 1.06 T; however, resistive transitions under magnetic fields suggests a higher B_c2, which hints at an unconventional nature of the superconductivity. The temperature dependence of the specific heat in 0 T suggests that the superconducting state is fully gapped. This material is an interesting candidate of a topological superconductor which may be realized by the strong spin-orbit coupling inherent to topological insulators.