Nontrivial superconductivity in topological MoTe2-xSx crystals

Topological Weyl semimetals (TWSs) with pairs of Weyl points and topologically protected Fermi arc states have broadened the classification of topological phases and provide superior platform for study of topological superconductivity. Here we report the nontrivial superconductivity and topological features of sulfur-doped T-d-phase MoTe2 with enhanced T-c compared with type-II TWS MoTe2. It is found that T-d-phase S-doped MoTe2 (MoTe2-xSx, x similar to 0.2) is a two-band s-wave bulk superconductor (similar to 0.13 meV and 0.26 meV), where the superconducting behavior can be explained by the s(+-)pairing model. Further, measurements of the quasi-particle interference (QPI) patterns and a comparison with band-structure calculations reveal the existence of Fermi arcs in MoTe2-xSx. More interestingly, a relatively large superconducting gap (similar to 1.7 meV) is detected by scanning tunneling spectroscopy on the sample surface, showing a hint of topological nontrivial superconductivity based on the pairing of Fermi arc surface states. Our work demonstrates that the T-d-phase MoTe2-xSx is not only a promising topological superconductor candidate but also a unique material for study of s(+-)superconductivity.