Scanning SQUID microscopy of ion-gel-gated MoS₂

Atomically thin exfoliated MoS₂ devices have been reported to superconduct at an n-type charge carrier density of ~ 10¹⁴ cm^-2 [1] with a critical temperature of approximately ~2 K in a monolayer [2]. To achieve the high charge carrier density ionic gating has been employed. Here, we report progress towards implementing ion-gel-gating of MoS₂ devices compatible with scanning probe measurements. To achieve this we spin coat an ionic gel to produce thicknesses below 1 μm, making it possible to bring a mesoscopic probe near the sample. This will allow us to perform local DC magnetometry and AC magnetic susceptibility measurements on these devices using scanning superconducting quantum interference device (SQUID) microscopy. By measuring the diamagnetic response of the superconducting state, we can identify spatial inhomogeneity in the transition temperature as well as the local London penetration depth at varying temperature.

[1] J. T. Ye et al. Science 338, 1193 (2012)
[2] D. Costanzo et al., Nature Nanotechnology 11, 339 (2016)