Exciton magnetotransport in two-dimensional systems: Weak-localization effects

摘要

We consider the effect of a magnetic field $B$ on the transport of neutralcomposite particles, excitons, in weakly disordered 2D systems. In the case ofclassical transport, when the interference of different paths is neglected, themagnetic field suppresses exciton transport, and the static diffusion constant$D(B)$ monotonically drops with $B$. When quantum-mechanical corrections due toweak localization are taken into account, $D(B)$ becomes a nonmonotonicfunction of $B$. In weak magnetic fields, where the magnetic length is muchlarger than the exciton Bohr radius, $l_B >> a_B$, a positive magnetodiffusioneffect is predicted, i.e., the exciton mobility should increase with $B$.