Superconductivity enhancement in the S-doped Weyl semimetal candidate MoTe_2

摘要

Two-dimensional transition-metal dichalcogenide (TMDs) MoTe_2 has attracted much attention due to its predicted Weyl semimetal state and a quantum spin Hall insulator in bulk and monolayer form, respectively. We find that the superconductivity in MoTe_2 single crystal can be greatly enhanced by the partial substitution of the Te ions by the S ones. The maximum superconducting temperature T_C of MoTe_(1.8)S_(0.2) single crystal is about 1.3 K. Compared with the parent MoTe_2 single crystal (T_C = 0.1K), nearly 13-fold in T_C is improved in the MoTe_(1.8)S_(0.2) one. The superconductivity has been investigated through the resistivity and magnetization measurements. MoTe_(2-x)S_x single crystals belong to weak coupling superconductors and the improvement of the superconductivity may be related to the enhanced electron-phonon coupling induced by the S-ion substitution. A dome-shaped superconducting phase diagram is obtained in the S-doped MoTe_2 single crystals. MoTe_(2-x)S_x materials may provide a new platform for our understanding of superconductivity phenomena and topological physics in TMDs.