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

Oleg L. Berman, Yurii E. Lozovik, David W. Snoke, Rob D. Coalson

Published 2005-12-24Version 1

Superfluidity in the quasi-two-dimensional (2D) system of spatially indirect magnetoexcitons in coupled quantum wells (CQW) and unbalanced two-layer electron system in high magnetic field $H$ is considered in the presence of a random field. The problem of the rare gas of magnetoexcitons with dipole-dipole repulsion in a random field has been reduced to the problem of the rare gas of dipole excitons without magnetic field with the effective magnetic mass of a magnetoexciton, which is a function of the magnetic field and parameters of the CQW, in an $H$-dependent effective random field. The density of the superfluid component $n_{s}$ and the temperature $T_{c}$ of the Kosterlitz-Thouless transition to a superfluid state are obtained as functions of magnetic field $H$, interlayer separation $D$ and the random field parameters $\alpha_{i}$ and $g_{i}$. For 2D magnetoexcitonic systems, the rise of the magnetic field $H$ and the interwell distance $D$ is found to increase the effective renormalized random field parameter $Q$ and suppress the superfluid density $n_s$ and the temperature of the Kosterlitz-Thouless transition $T_c$. The suppressing influence of $D$ on $n_s$ and $T_c$ in strong magnetic filed is opposite to the case without magnetic field, when $n_s$ and $T_c$ increase with the rise of $D$ at fixed total exciton density $n$. It is shown that in the presence of the disorder at sufficiently large magnetic field $H$ or parameters of the disorder there is no superfluidity at any exciton density.