Enhanced critical field and anomalous metallic state in two-dimensional centrosymmetric 1T′−WS2

Abstract

Layered transition-metal chalcogenide material (TMD) offers a platform to investigate two-dimensional (2D) superconductivity. Here, we report an electrical transport study of 2D centrosymmetric superconductor $1{T}^{\ensuremath{'}}\text{\ensuremath{-}}\mathrm{W}{\mathrm{S}}_{2}$. For a typical five-layer sample, the 2D superconductivity is revealed in Berezinskii-Kosterlitz-Thouless (BKT) transition with the characteristic temperature ${T}_{BKT}\ensuremath{\sim}5\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. The superconductivity is observed with a strong resist against the in-plane magnetic field. We find that the critical in-plane magnetic field is \ensuremath{\sim}3 times the Pauli paramagnetic limit ${B}_{p}$, with effective Zeeman-type spin-orbital coupling $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{{\ensuremath{\beta}}_{\mathrm{SO}}}\ensuremath{\sim}2.8\phantom{\rule{0.16em}{0ex}}\mathrm{meV}$. In addition, we find the magnetoresistance trend to saturate at low temperature, suggesting anomalous quantum metallic states. These findings might stimulate further investigations on the correlation between superconductivity and symmetry of 2D superconductors, as well as the quantum metallic states at low temperature with finite magnetic field.