TRANSPORT-PROPERTIES OF MAGNETOEXCITONS IN COUPLED QUANTUM-WELLS

The transport times tau(P) and the mean free paths of magnetoexcitons in a quantum well and of spatially direct and indirect magnetoexcitons in coupled quantum wells in a random potential produced by thickness fluctuations of the quantum wells or a random distribution of impurity centers in quantum wells (P is the magnetic momentum of an exciton) a re calculated. The function tau(P) is nonmonotonic, but as the distanc e D between the quantum wells increases, the maximum tau(max)(P) gradu ally vanishes in the presence of scattering by surface terraces. As th e magnetic field (H) increases, tau(0) decreases as 1/root H for D muc h less than l (l = root (h) over bar c/eH is the magnetic length) and as 1/H-2 for D much greater than l. The behavior of the computed value s of tau for large H agrees qualitatively with the experimental data. The mean free path length of a magnetoexciton exhibits at P not equal 0 a maximum whose magnitude decreases as the parameter D/l increases, (C) 1998 American Institute of Physics. [S1063-7826(98)01805-5].