Exciton crystal melting and destruction by disorder in bilayer quantum hall system with total filling factor one

TL;DR

This paper investigates how disorder and layer imbalance affect exciton crystals in bilayer quantum Hall systems, revealing phase transitions including melting into superfluidity and a locking transition impacting conductance.

Contribution

It introduces the theoretical analysis of exciton crystal melting and disorder-induced phase transitions in bilayer quantum Hall systems with high layer imbalance.

Findings

Exciton Wigner crystal can melt into a superfluid phase.

Disorder causes a locking/decoupling transition in electron and hole crystals.

Layer separation influences the transition and conductance changes.

Abstract

Bilayer quantum hall system with total filling factor 1 was studied in the regime of heavy layer imbalance in a recent transport experiment [Zeng2023, arXiv:2306.16995], with intriguing new findings. We demonstrate in this paper that 1) the exciton Wigner crystal in this regime can melt into a superfluid phase, giving rise to re-entrant superfluid behavior; 2) in the presence of disorder, electron and hole Wigner crystals in the two layers go through a locking/decoupling transition as layer separation increases, resulting in a sudden change in the counter flow conductance. Comparison will be made with the findings of experiments.