Intrinsic superconductivity in transition metal dichalcogenides
We will fabricate TMD-based hybrid materials with a clean 2D superconducting state with very long mean free path in the normal state to facilitate the realization of a robust topological superconducting state. A 2H-type monolayer TMD can host a nodal topological superconductor where the nodal points appear when Ising spin-orbit interaction vanishes at certain points in the Brillouin zone. A strong Ising protection that disappears in one pocket gets reversely Ising-protected in the other pocket. For MoS2 and WS2, the Ising superconductivity is in the conduction band with protection residing at the zone edge. The competing pocket can be controllably introduced by adding a second layer, resulting in a Q pocket centered between the zone corner and zone center. We will use DFT calculations to predict the optimal location of the Fermi level. Simple devices will be fabricated to allow gate-controlled scanning probe spectroscopy, which we will use to study the superconductivity, and zero-energy states (see third sub-project).