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

The paper considers the effect of a magnetic field B on the transport of neutral composite particles, namely excitons, in weakly disordered two-dimensional (2D) systems. In the case of classical transport (when the interference of different paths is neglected), the magnetic field suppresses exciton transport, and the static diffusion constant D(B) monotonically drops with B. When quantum-mechanical corrections due to weak localization are taken into account, Lf(B) becomes a nonmonotonic function of B. In weak magnetic fields, where the magnetic length is much larger than the exciton Bohr radius, l(B) = (<(h)over bar c/eB>)(1/2) much greater than a(B) = <epsilon(h)over bar (2)/mu e(2)>, a positive magnetodiffusion effect is predicted, i.e, the exciton mobility should increase with B. (C) 1998 American Institute of Physics.