Speaker
Prof.
Herbert Fertig
(Indiana University)
Description
In this talk I will review some of the ideas and experiments
suggesting that quantum Hall bilayers near filling factor 1
may form an exciton condensate state, leading to the
possibility of superflow for counterflowing currents in the
two layers. In real experiments, dissipationless transport
appears to emerge, it at all, only at zero temperature, so
that the observed superfluidity is at best imperfect. This
appears likely to be due to disorder, which can flood the
system with merons -- vortex-like excitations -- even at
zero temperature. I will discuss a "coherence network"
model which incorporates the presence of these objects in
the groundstate, and qualitatively captures much of the
physics observed in experiment. Finally I will discuss the
results of drag experiments in this system, where interlayer
coherence and quantum Hall physics conspire in such a way
that one can probe different types of merons with
measurements on different layers.
Primary author
Prof.
Herbert Fertig
(Indiana University)
