Superconductivity in the Doped Topological InsulatorCuxBi2Se3under High Pressure

We report a high-pressure single crystal study of the topological superconductor ${\mathrm{Cu}}_{x}{\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$. 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.