Theory of Activated Transport in Bilayer Quantum Hall Systems

We analyze the transport properties of bilayer quantum Hall systems at total filling factor nu = 1 in drag geometries as a function of interlayer bias, in the limit where the disorder is sufficiently strong o unbind meron-antimeron pairs, the charged topological defects of the system. We compute the ypical energy barrier for these objects to cross incompressible regions within the disordered system using a Hartree-Fock approach, and show how this leads to multiple activation energies when the ystem is biased. We then demonstrate using a bosonic Chern-Simons theory that in drag geometries, urrent in a single layer directly leads to forces on only two of the four types of merons, inducing dissipation only in the drive layer. Dissipation in the drag layer results from interactions among he merons, resulting in very different temperature dependences for the drag and drive layers, in qualitative agreement with experiment. We conclude with predictions for future experiments.