Large upper critical field in ion-gated MoS2 superconductivity

Molybdenum disulfide (MoS$_2$) is an archetypal two-dimensional (2D) materials beyond graphene, and are attracting significant attention due to its multiple functionalities, including field effect transistor, photoluminescence, and valleytronics. An additional function of MoS$_2$ is electric-field-induced superconductivity, realized by ionic gating. In this presentation, we report anisotropic superconducting upper critical fields {\it H}$_{c2}$ in electric-field-induced superconductivity on MoS$_2$, measured under high magnetic fields up to 55 T. We found that the in-plane {\it H}$_{c2}$ increased with squarer root near {\it T}$_c$, reflecting the purely two-dimensionality of electric-field-induced superconductivity, and possibly reached nearly 60 T at $T \to 0 K$. This value is around 5 times larger than the normal Pauli limit simply expected from the {\it T}$_c$ value. Such an enhancement is possibly caused by the strong out-of-plane Zeeman filed, which is the consequence of the inplane-broken inversion symmetry of MoS$_2$ monolayer coupled with the spin orbit interactions.