Triplet pairing driven by Hund's coupling in doped monolayer MoS$_2$

TL;DR

This paper uses a theoretical model and fRG analysis to explore how electron-electron interactions induce triplet superconductivity in doped monolayer MoS$_2$, highlighting the role of Hund's coupling and ferromagnetic fluctuations.

Contribution

It reveals that Hund's coupling and multiorbital effects drive triplet pairing in doped MoS$_2$, a novel mechanism distinct from graphene.

Findings

Odd-parity f-wave pairing at low doping

Critical temperature increases with doping

Ferromagnetic fluctuations promote triplet pairing

Abstract

We investigate superconducting pairing driven by electron-electron interactions in a theoretical model for monolayer MoS$_2$ with the temperature-flow functional renormalization group(fRG). At low doping, the dominant instability is toward odd-parity pairing with $f$-wave Mo-nearest-neighbor structure. We compute the fRG phase diagram versus electron doping below the van Hove filling of the conduction band. In the superconducting regime, the critical temperature grows with doping, comparable to the experiments. Near van Hove filling the system favors a ferromagnetic state. We demonstrate that the triplet pairing is driven by ferromagnetic fluctuations and that the multiorbital nature of the conduction band as well as the Hund's coupling appear crucial in making the physics of MoS$_2$ different from e.g. doped graphene.