Diffusive traversal time: Effective area in magnetically induced interference

Classical diffusion through a disordered region, connected to leads with unscattered carrier motion, can be characterized by reflection and transmission probabilities and by the time it takes a carrier to diffuse through the sample. This traversal time is found, following a suggestion by Pippard, by letting carriers be absorbed along the way and calculating the resulting reduction in transmission. The traversal time for diffusion is used to calculate the mean square area enclosed between two randomly selected paths in a disordered conductor. In the presence of a magnetic field, this area determines the field scale over which the magnetoresistance exhibits uncorrelated random fluctuations. © 1987 The American Physical Society.