Unconventional superconductivity mediated by exciton density wave fluctuations

TL;DR

This paper explores how exciton density wave fluctuations in charge-imbalanced bilayer semiconductors can mediate unconventional superconductivity, with potential for electrical control and unique interlayer pairing states.

Contribution

It demonstrates the theoretical possibility of electrically tunable exciton-mediated superconductivity and identifies conditions for density wave order in bilayer heterostructures.

Findings

Goldstone mode mediates attractive interactions leading to superconductivity

Low-energy exciton modes support interlayer pair-density wave superconductivity

Gating conditions can induce exciton density wave order

Abstract

Synthetic platforms afford an unparalleled degree of controllability in realizing strongly-correlated phases of matter. In this work, we study the possibility of electrically tunable exciton-mediated superconductivity arising in charge-imbalanced bilayer semiconductors. Focusing on the case of a bilayer semiconductor heterostructure, we identify the gating conditions required to achieve exciton density wave order within a self-consistent Hartree-Fock approximation. We analyze the role of the coupling of excitonic fluctuations to the fermionic charge carriers to find that the Goldstone mode of the density wave order can mediate attractive interactions leading to superconductivity. Furthermore, when the system is close to the density wave ordering, the interactions mediated by low-energy exciton modes can support an interlayer pair-density wave superconductor of anisotropic character. We discuss experimental signatures associated with these phenomena.