Ising superconductivity and Majorana fermions in transition-metal dichalcogenides

Due to its noncentrosymmetric lattice structure, a monolayer of transition metal dichalcogenides (TMD) possesses a very special type of spin-orbit coupling (SOC) called Ising SOC. Unlike Rashba SOC, Ising SOC pins electron spins to the out-of-plane rather than the in-plane direction. In TMD materials, the Ising SOC is quite strong and substantially enhances the in-plane upper critical field of their superconducting state. Despite this, the authors show here that the Ising SOC can in fact lead to spin-triplet Cooper pairing with electrons spins pointing in the in-plane direction. Such pairing induces a topological superconducting state in spin-polarized proximity coupled wires and generates Majorana end states. So-formed Majorana states can be more accessible experimentally due to the strong Ising SOC and a wider topologically nontrivial regime.