Ising Superconductivity and Majorana Fermions in Transition Metal Dichalcogenides

TL;DR

This paper explores how Ising spin-orbit coupling in monolayer transition metal dichalcogenides leads to equal-spin triplet pairing and the potential realization of topological superconductors hosting Majorana fermions.

Contribution

It demonstrates that Ising SOC induces equal-spin triplet Cooper pairs and proposes a method to realize topological superconductivity with Majorana states in TMD-based heterostructures.

Findings

Ising SOC generates equal-spin triplet pairs with in-plane spin polarization.

Triplet pairs can induce topological superconductivity in half-metal wires.

Detectable differences between Ising and Rashba superconductors are discussed.

Abstract

In monolayer transition metal dichalcogenides (TMDs), electrons in opposite $K$ valleys are subject to opposite effective Zeeman fields, which are referred to as Ising spin-orbit coupling (SOC) fields. The Ising SOC, originated from in-plane mirror symmetry breaking pins the electron spins in out-of-plane directions, and results in the newly discovered Ising superconducting states with strongly enhanced upper critical fields. In this work, we show that the Ising SOC generates equal-spin triplet Cooper pairs with spin polarization in the in-plane directions. Importantly, the spin-triplet Cooper pairs can induce superconducting pairings in a half-metal wire placed on top of the TMD and result in a topological superconductor with Majorana end states. Direct ways to detect equal-spin triplet Cooper pairs and the differences between Ising superconductors and Rashba superconductors are discussed.