Topological superconductor in quasi-one-dimensional Tl[subscript 2 − x]Mo[subscript 6]Se[subscript 6]

Abstract

We propose that the quasi-one-dimensional molybdenum selenide compound Tl[subscript 2−x]Mo[subscript 6]Se[subscript 6] is a time-reversal-invariant topological superconductor induced by intersublattice pairing, even in the absence of spin-orbit coupling (SOC). No noticeable change in superconductivity is observed in Tl-deficient (0≤x≤0.1) compounds. At weak SOC, the superconductor prefers the triplet d vector lying perpendicular to the chain direction and two-dimensional E[subscript 2u] symmetry, which is driven to a nematic order by spontaneous rotation symmetry breaking. The locking energy of the d vector is estimated to be weak and hence the proof of its direction would rely on tunneling or phase-sensitive measurements.