Superconductivity in the doped topological insulator Cu${}_x$Bi${}_2$Se${}_3$ under high pressure

Abstract

We report a high-pressure single crystal study of the topological superconductor Cu${}_x$Bi${}_2$Se${}_3$. Resistivity measurements under pressure show superconductivity is depressed smoothly. At the same time the metallic behavior is gradually lost. The upper critical field data $B_{c2}(T)$ under pressure collapse onto a universal curve. The absence of Pauli limiting and the comparison of $B_{c2}(T)$ to a polar state function point to spin-triplet superconductivity, but an anisotropic spin-singlet state cannot be discarded completely.

5 pages, 4 figures; accepted for publication in PRL