Interaction and disorder in bilayer counterflow transport at filling factor one

TL;DR

This paper investigates how interactions and disorder affect counterflow superfluid transport in GaAs bilayer hole systems at total filling factor one, revealing the roles of density imbalance and vortices.

Contribution

It provides new insights into the effects of layer density imbalance and disorder on counterflow transport properties at $ u=1$ in bilayer systems.

Findings

Counterflow Hall resistivity decreases with reduced density.

Counterflow longitudinal resistivity is largely unaffected by density changes.

Layer imbalance significantly impacts $ ho_{xx}$, indicating vortex-related dissipation.

Abstract

We study high mobility, interacting GaAs bilayer hole systems exhibiting counterflow superfluid transport at total filling factor $\nu=1$. As the density of the two layers is reduced, making the bilayer more interacting, the counterflow Hall resistivity ($\rho_{xy}$) decreases at a given temperature, while the counterflow longitudinal resistivity ($\rho_{xx}$), which is much larger than $\rho_{xy}$, hardly depends on density. On the other hand, a small imbalance in the layer densities can result in significant changes in $\rho_{xx}$ at $\nu=1$, while $\rho_{xy}$ remains vanishingly small. Our data suggest that the finite $\rho_{xx}$ at $\nu=1$ is a result of mobile vortices in the superfluid created by the ubiquitous disorder in this system.