Unconventional superconductivity from magnetism in transition metal dichalcogenide

TL;DR

This paper explores how magnetism influences superconductivity in monolayer transition metal dichalcogenides, revealing diverse and tunable pairing states, including an exotic equal-spin triplet pairing induced by noncollinear spin orientations.

Contribution

It demonstrates the emergence of various superconducting pairings, especially an exotic equal-spin triplet, due to the interplay of spin-orbit coupling and magnetic exchange fields in TMD monolayers.

Findings

Multiple superconducting order parameters identified.

Existence of an exotic equal-spin triplet pairing.

Superconducting states are highly tunable via exchange field.

Abstract

We investigate proximity-induced superconductivity in monolayers of transition metal dichalcogenides (TMDs) in the presence of an externally generated exchange field. A variety of superconducting order parameters is found to emerge from the interplay of magnetism and superconductivity, covering the entire spectrum of possibilities to be symmetric or antisymmetric with respect to the valley and spin degrees of freedom, as well as even or odd in frequency. More specifically, when a conventional \emph{s}-wave superconductor with singlet Copper pairs is tunnel-coupled to the TMD layer, both spin-singlet and triplet pairings between electrons from the same and opposite valleys arise due to the combined effects of intrinsic spin-orbit coupling and a magnetic-substrate-induced exchange field. As a key finding, we reveal the existence of an exotic even-frequency triplet pairing between equal-spin electrons from different valleys, which arises whenever the spin orientations in the two valleys are noncollinear. All types of superconducting order turn out to be highly tunable via straightforward manipulation of the external exchange field.