EFFECTS OF A FINITE ELECTRIC-FIELD ON THE LOCALIZATION IN ANISOTROPIC2-DIMENSIONAL SYSTEMS

The direct influence of a d.c. electric field on weak localization is investigated on the basis of a quantum diffusion model for an anisotro pic two-dimensional electron gas. The anisotropy is treated both in a model of anisotropic effective masses and in a tight-binding model for parallel chains. The crossover of the delocalization edge from a powe r-law 1D-like dependence to an exponential decrease, characteristic fo r a 2D system, is investigated. The appearance of a delocalization edg e gives rise to a long-time power-law current relaxation according to j(t) similar to 1/root t, independently of the anisotropy.