Local magnetic measurements of a few-layer van der Waals superconductor

Measurements of thermodynamic properties of few-layer van der Waals superconductors are scarce due to the inherently small volume of mechanically exfoliated samples. Here we measure the magnetic susceptibility of a van der Waals superconductor by using local magnetic measurements enabled by scanning SQUID microscopy. Specifically, we study transition metal dichalcogenide MoS2 which exhibits a superconducting dome with a maximum critical temperature of nearly 10 K in ionic-gated few-layer devices. We combine the magnetic measurements with simultaneous electrical transport and map out changes in superfluid stiffness as a function of temperature and carrier density across the dome. We observe magnetic signatures consistent with a Kosterlitz-Thouless transition, and report our progress towards extracting absolute values of the superfluid stiffness and density from these measurements.