Interaction and disorder in bilayer counterflow transport at filling factor one

Abstract

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