Competition of Density Waves and Superconductivity in Twisted Tungsten Diselenide

TL;DR

This paper uses a functional renormalization group approach to explore the complex interplay of density waves and superconductivity in twisted tungsten diselenide, revealing mixed-parity and topological superconducting states.

Contribution

It introduces an unbiased theoretical analysis of competing phases in tWSe$_2$ beyond mean-field methods, mapping their phase diagram and identifying signatures for experiments.

Findings

Identification of mixed-parity superconducting order parameters.

Discovery of incommensurate density wave states.

Characterization of interaction-driven phases in tWSe$_2$.

Abstract

Evidence for correlated insulating and superconducting phases around regions of high density of states was reported in the strongly spin-orbit coupled van-der Waals material twisted tungsten diselenide (tWSe$_2$). We investigate their origin and interplay by using a functional renormalization group approach that allows to describe superconducting and spin/charge instabilities in an unbiased way. We map out the phase diagram as function of filling and perpendicular electric field, and find that the moir\'e Hubbard model for tWSe$_2$ features mixed-parity superconducting order parameters with $s/f$-wave and topological $d/p$-wave symmetry next to (incommensurate) density wave states. Our work systematically characterizes competing interaction-driven phases in tWSe$_2$ beyond mean-field approximations and provides guidance for experimental measurements by outlining the fingerprint of correlated states in interacting susceptibilities.