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
Abstract
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
α
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.