The role of density imbalance in the vT = 1 exciton condensate state for electron bilayer systems

Abstract

We report on our experimental work involving the T = 1 exciton condensate in independently contacted bilayer two-dimensional electron systems. A phase diagram between the weakly coupled ( U = 1/2, L = 1/2) phase and the strongly coupled T = 1 phase is experimentally investigated as a function of d /B and electron density imbalance n ( [n L - n U]/n T) using a drag current configuration. For imbalanced electron layer densities, small interlayer imbalances lead to strengthening of the excitonic phase. Here density imbalance leads to a phase boundary in the drag layer which is symmetric around zero imbalance. Surprisingly this behavior is not seen for drive,xx , where an unusual asymmetric behavior around zero imbalance occurs. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)