title: Phase diagram for quantum hall bilayers at nu=1.
abstract: We present a phase diagram for a double quantum well bilayer electron gas in the quantum Hall regime at a total filling factor nu=1, based on exact numerical calculations of the topological Chern number matrix and the (interlayer) superfluid density. We find three phases: a quantized Hall state with pseudospin superfluidity, a quantized Hall state with pseudospin "gauge-glass" order, and a decoupled composite Fermi liquid. Comparison with experiments provides a consistent explanation of the observed quantum Hall plateau, Hall drag plateau, and vanishing Hall drag resistance, as well as the zero-bias conductance peak effect, and suggests some interesting points to pursue experimentally.
authors.affiliation: Department of Physics and Astronomy, California State University, Northridge, California 91330, USA.
authors.forename: D N
authors.initials: DN
authors.lastname: Sheng
authors.forename: Leon
authors.initials: L
authors.lastname: Balents
authors.forename: Ziqiang
authors.initials: Z
authors.lastname: Wang