Superconducting properties of purely distorted transition metal dichalcogenides

The distorted phases (such as 2M) of transition metal dichalcogenides (TMDCs) exhibit exotic physical properties, such as superconductivity, topological energy gap, and Majorana bound states [1-2]. However, because the distorted phases are metastable and they usually appear in domains within their thermodynamically stable counterpart, transport experiments of these phases have been limited. Here we present a TMDC with a purely distorted phase that features unconventional superconductivity with an extremely anisotropic upper critical field. Remarkably, the critical field along the in-plane direction violates the well-established Pauli limit. We find that this superconductor shows a surprisingly large critical current density, which is two orders of magnitude higher than that in typical two-dimensional superconductors. Our work provides a promising route to understand the nature of superconductivity in distorted TMDCs.