Superfluidity of 'dirty' indirect magnetoexcitons in coupled quantum wells in high magnetic field

We present a theory of superfluidity in the quasi-two-dimensional system of spatially indirect magnetoexcitons in coupled quantum wells in the presence of a random field. The problem of a dilute gas of magnetoexcitons with dipole dipole repulsion in the limit of high magnetic field can be mapped to the problem of a dilute gas of two-dimensional excitons in a random field without magnetic field. The density of the superfluid component n(s) and the critical temperature T-c of the Kosterlitz-Thouless transition to a superfluid state are obtained as functions of magnetic field H, electron-hole spatial separation D, and the random field parameters. For two-dimensional magnetoexciton systems, increasing the magnetic field H and the distance D suppresses the superfluid density and the critical temperature of the Kosterlitz-Thouless transition. The influence of the interwell distance D on ns and Tc in strong magnetic field is opposite to the case without magnetic field, where ns and Tc increase with increasing D, for fixed total exciton density n. We show that in the presence of the disorder there must be a quantum phase transition from a superfluid to a disordered phase at T = 0 as the magnetic field H is varied. There is no superfluidity at any exciton density in the presence of the disorder at sufficiently large magnetic field H or sufficiently large disorder.