Pair-density-wave and chiral superconductivity in twisted bilayer transition-metal-dichalcogenides

TL;DR

This paper theoretically predicts the emergence of topological chiral superconductivity and spin-polarized pair density wave states in twisted bilayer transition-metal-dichalcogenides under certain conditions, using renormalization group analysis.

Contribution

It introduces a theoretical framework showing how unconventional topological and spin-polarized superconducting states can arise in twisted bilayer TMDs with electric fields.

Findings

Topological chiral superconducting states with Chern numbers 1, 2, 4 are predicted.

Spin-polarized pair density wave superconductivity can emerge under specific electric and magnetic fields.

Proposed experimental probes include spin-polarized STM and superconducting diode effects.

Abstract

We theoretically explore possible unconventional superconductivity induced by weak repulsive interactions in twisted bilayer TMD (e.g. WSe$_2$) in the presence of an out-of-plane electric field. Using renormalization group (RG) analysis, we show that topological chiral superconducting states with Chern number $\mathcal{N}=1,2,4$ (namely $p+ip$, $d+id$, $g+ig$) appear over a large parameter region with moire filling factor around $n=1$. At some special values of applied electric field and in the presence of a weak out-of-plane Zeeman field, spin-polarized pair density wave (PDW) superconductivity can emerge. This spin-polarized PDW state can be probed by experiments such as spin-polarized STM measuring spin-resolved pairing gap and quasi-particle interference. Moreover, the spin-polarized PDW could lead to spin-polarized superconducting diode effect.