Recently, it was experimentally realized that 2D superconducting transition metal dichalcogenides (TMD) such as gated MoS2 and monolayer NbSe2 have in-plane upper critical magnetic fields much higher than the Pauli limit. This is due to the so-called Ising spin-orbit coupling (SOC) of TMD which pins the electron spins along the out-of-plane directions and protects the Cooper pairs from in-plane magnetic fields. However, many TMD materials with extremely large Ising SOC, in the order of a few hundred meV, are not superconducting. In this work, we show that TMD materials can induce strong Ising SOC on ordinary s-wave superconductors through proximity effect. By solving the self-consistent gap equation of the TMD/superconductor heterostructure, we found that the Hc2 of the s-wave superconductor can be strongly enhanced. Importantly, when the in-plane field is larger than the Pauli limit field and weaker than Hc2, the heterostructure becomes a nodal topological superconductor which supports Majorana flat bands.
@article{arxiv.1604.04898,
title = {Proximity effect and Ising superconductivity in superconductor/transition metal dichalcogenide heterostructures},
author = {Ryohei Wakatsuki and K. T. Law},
journal= {arXiv preprint arXiv:1604.04898},
year = {2016}
}