Enhancement of the Upper Critical Field in Disordered Transition Metal Dichalcogenide Monolayers

We calculate the effect of impurities on the superconducting phase diagram of transition metal dichalcogenide monolayers in the presence of an in-plane magnetic field. Because of strong intrinsic spin-orbit coupling, the upper critical field greatly surpasses the Pauli limit at low temperatures. We find that it is insensitive to intravalley scattering and, ultimately, limited by intervalley scattering. We use parameters extracted from the weak-localization signal of n-doped transition metal dichalcogenide monolayers in the normal state to compare our predictions for the upper critical line with the experimentally measured ones.