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

Zhang, Yong; Fei, Fucong; Liu, Ruxin; Zhu, Tongshuai; Chen, Bo; Qiu, Tianyu; Zuo, Zewen; Guo, Jingwen et al. · Adv Mater · 2023

basic_science · Level V

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Abstract

2D transition metal dichalcogenides are promising platforms for next-generation electronics and spintronics. The layered Weyl semimetal (W,Mo)Te<sub>2</sub> series features structural phase transition, nonsaturated magnetoresistance, superconductivity, and exotic topological physics. However, the superconducting critical temperature of the bulk (W,Mo)Te<sub>2</sub> remains ultralow without applying a high pressure. Here, the significantly enhanced superconductivity is observed with a transition temperature as large as about 7.5 K in bulk Mo<sub>1-</sub> <sub>x</sub> Ta<sub>x</sub> Te<sub>2</sub> 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<sub>d</sub> -phase Mo<sub>1-</sub> <sub>x</sub> Ta<sub>x</sub> Te<sub>2</sub> (x = 0.08), indicating the possible emergence of unconventional mixed singlet-triplet superconductivity owing to the inversion symmetry breaking. This work provides a new pathway for exploring the exotic superconductivity and topological physics in transition metal dichalcogenides.