Gossamer Superconductivity in Moir\'e WSe$_2$ Bilayer

TL;DR

This paper proposes that the recently observed superconductivity in twisted WSe2 bilayers has a gossamer nature, arising from a delicate balance of Coulomb interactions and kinetic effects within an effective Hubbard model.

Contribution

It introduces a theoretical framework mapping moiré WSe2 to an extended Hubbard model and predicts a chiral d+id superconducting phase stabilized by Coulomb interactions.

Findings

Moderate Coulomb repulsion suppresses charge fluctuations but allows mobile doublons and holes.

The interplay of kinetic hoppings and superexchange stabilizes a chiral d+id superconducting phase.

Superconductivity vanishes rapidly with doping, matching experimental results.

Abstract

Moir\'e transition metal dichalcogenides have served as a versatile platform for simulating Hubbard physics. Recent experiments have identified robust superconductivity in moir\'e bilayer WSe$_2$ for certain twist angles. Here, we propose the gossamer nature of the superconductivity recently discovered at half-filling and zero displacement field in twisted WSe$_2$. By mapping the moir\'e continuum system to an effective extended single-orbital Hubbard model on the triangular lattice, we employ renormalized mean-field theory to investigate the strong-coupling phase diagram. We find that a moderate Coulomb repulsion partially suppresses charge fluctuations while preserving a finite density of mobile doublons and holes. In this regime, the interplay between extended kinetic hoppings and antiferromagnetic superexchange stabilizes a chiral $d+id$ superconducting phase. Our results naturally account for the twist-angle-dependent evolution from a Mott insulator to a superconductor and eventually to a correlated metal. Furthermore, the model demonstrates that this half-filled pairing state vanishes rapidly upon density doping, consistent with experimental observations.