Superconducting pairing symmetry in MoTe2

Topological superconductors have long been sought for their potential use in quantum computing. The type-II Weyl semimetal MoTe2 is an obvious candidate, exhibiting a superconducting state below 500 mK at ambient pressure, but the question remains whether the pairing is conventional s++ or topological s+-. The application of external pressure favors the superconducting state in MoTe2 and suppresses the structural transition from 1T' to Td. The competition between the two structures leads to a mixed phase that strongly enhances the disorder present in the system, remarkably without affecting the superconducting transition temperature, in contrast to the expectation of s+- pairing superconductivity. Our thorough analysis of the electrical and Hall resistivities as a function of pressure yields the most accurate temperature-pressure phase diagram available to date for MoTe2 and a detailed view of the relationship between disorder and superconductivity, supporting a conventional s++ pairing symmetry.