Two Dimensional Ising Superconductivity in Gated MoS$_{2}$

TL;DR

This paper demonstrates that gating-induced Zeeman fields in monolayer MoS$_{2}$ create an Ising superconductor, significantly enhancing in-plane critical magnetic fields and protecting superconductivity against magnetic destruction.

Contribution

It provides the first experimental evidence of Ising superconductivity in a 2D transition metal dichalcogenide, revealing how intrinsic spin-orbit coupling stabilizes superconductivity.

Findings

In-plane critical field exceeds Pauli limit by over ten times.

Gating enhances Zeeman field, strengthening spin pinning.

Superconductivity is protected by intrinsic spin-orbit coupling in monolayer MoS$_{2}$.

Abstract

The Zeeman effect, which is usually considered to be detrimental to superconductivity, can surprisingly protect the superconducting states created by gating a layered transition metal dichalcogenide. This effective Zeeman field, which is originated from intrinsic spin orbit coupling induced by breaking in-plane inversion symmetry, can reach nearly a hundred Tesla in magnitude. It strongly pins the spin orientation of the electrons to the out-of-plane directions and protects the superconductivity from being destroyed by an in-plane external magnetic field. In magnetotransport experiments of ionic-gate MoS$_{2}$ transistors, where gating prepares individual superconducting state with different carrier doping, we indeed observe a spin- protected superconductivity by measuring an in-plane critical field $\textit{B}$$_{c2}$ far beyond the Pauli paramagnetic limit. The gating-enhanced $\textit{B}$$_{c2}$ is more than an order of magnitude larger compared to the bulk superconducting phases where the effective Zeeman field is weakened by interlayer coupling. Our study gives the first experimental evidence of an Ising superconductor, in which spins of the pairing electrons are strongly pinned by an effective Zeeman field.