Multiple odd-parity superconducting phases in bilayer transition metal dichalcogenides

TL;DR

This paper explores unconventional odd-parity superconducting phases in bilayer transition metal dichalcogenides, highlighting the role of ferromagnetic fluctuations, spin-orbit coupling, and the potential for topological chiral p-wave states.

Contribution

It demonstrates the stabilization of multiple odd-parity superconducting phases, including a topological chiral p-wave state, driven by ferromagnetic fluctuations and spin-orbit interactions in bilayer TMDs.

Findings

Ferromagnetic fluctuations favor odd-parity spin-triplet superconductivity.

An odd-parity f-wave state is stabilized over a wide carrier density range.

A topological chiral p-wave state emerges with moderate Zeeman spin-orbit coupling.

Abstract

We study unconventional superconductivity in a two-dimensional locally noncentrosymmetric triangular lattice. The model is relevant to bilayer transition metal dichalcogenides with 2H$_b$ stacking structure, for example. The superconducting instability is analyzed by solving the linearized Eliashberg equation within the random phase approximation. We show that ferromagnetic fluctuations are dominant owing to the existence of disconnected Fermi pockets near van Hove singularity, and hence odd-parity spin-triplet superconductivity is favored. In the absence of the spin-orbit coupling, we find that odd-parity $f$-wave superconducting state is stabilized in a wide range of carrier density and interlayer coupling. Furthermore, we investigate impacts of the layer-dependent staggered Rashba and Zeeman spin-orbit coupling on the superconductivity. Multiple odd-parity superconducting phase diagrams are obtained as a function of the spin-orbit coupling and Coulomb interaction. Especially, a topological chiral $p$-wave pairing state is stabilized in the presence of a moderate Zeeman spin-orbit coupling. Our results shed light on a possibility of odd-parity superconductivity in various ferromagnetic van der Waals materials.