crystals

Topological Weyl semimetals (TWSs) and topological Dirac semimetals have broadened the classification of topological phases and provide new platforms for studying topological superconductivity. Here, we report a systematic study of superconductivity in sulfur-doped T_d-phase MoTe₂ with enhanced T_c compared with type-II TWS MoTe_2. We found that T_d-phase S-doped MoTe₂ (MoTe_2−xS_x, x ∼ 0.2) is a two-band s-wave bulk superconductor (superconducting gap∼0.13 meV and 0.26 meV), where the superconducting behavior can be explained by the s₊₋ pairing model. We also used scanning tunneling spectroscopy to detect a relatively large surface superconducting gap (∼1.7 meV), suggestive of topologically nontrivial superconductivity based on the pairing of Fermi arc surface states. Indeed, a comparison of the quasi-particle interference patterns with band-structure calculations indicates Fermi arcs in MoTe_2−xS_x. Our results demonstrates that the T_d-phase MoTe_2−xS_x might be a promising topological superconductor candidate and also a unique material for studying s₊₋ superconductivity.