Enhanced Superconductivity and Upper Critical Field in Ta-Doped Weyl Semimetal T d -MoTe 2 .

Two-dimensional transition metal dichalcogenides are promising platforms for next-generation electronics and spintronics. The layered Weyl semimetal (W,Mo)Te 2 series features structural phase transition, nonsaturated magnetoresistance, superconductivity, and exotic topological physics. However, the superconducting critical temperature of the bulk (W,Mo)Te 2 remains ultralow without applying a high pressure. Here, we observe the significantly enhanced superconductivity with a transition temperature as large as about 7.5 K in bulk Mo 1- x Ta x Te 2 single crystals upon Ta doping (0 ≤ x ≤ 0.22), which is attributed to an enrichment of density of states at the Fermi level. In addition, an enhanced perpendicular upper critical field of 14.5 T exceeding the Pauli limit is also observed in T d -phase Mo 1- x Ta x Te 2 (x = 0.08), indicating the possible emergence of unconventional mixed singlet-triplet superconductivity owing to the inversion symmetry breaking. Our work provides a new pathway for exploring the exotic superconductivity and topological physics in transition metal dichalcogenides. This article is protected by copyright. All rights reserved.