Identifying topological superconductivity in two-dimensional transition-metal dichalcogenides

We study the superconducting pairing instabilities and gap functions for prototypical two-dimensional (2D) transition-metal dichalcogenides (TMDCs) WS₂, MoTe₂, and MoS₂ in the 2H phase under both hole and electron doping at 10 K. Our first-principles quantum many-body Green's function approach allows us to treat the full d and p manifold of orbitals with strong spin-orbit coupling, yielding pairing predictions with material-specific detail. The resulting gap functions exhibit a variety of mixed-parity superconducting states, including s, p, d, f, d±id, and p±ip pairing modes. In particular, we predict 3% and 4% hole-doped WS₂ to be a chiral p±ip topological superconductor. For 1% hole-doped MoS₂, we find a competition between three doubly degenerate chiral and nonchiral instabilities. Overall, the relative pairing strengths are found to follow the Fermi-surface topology, due to nesting between the Fermi-surface sheets. Finally, we discuss our predictions in relation to available experimental data and classify the topology of the predicted superconducting pairing symmetries.