Giant Magnetoresistance in Lateral Surface Superlattices

We investigate the low-field magnetoresistance ñxx perpendicular to a one- dimensional periodic potential which is imposed upon a two-dimensional electron gas in GaAs-AlxGa1-xAs heterojunctions. Distinct low-field anomalies and a crossover from positive to large negative magnetoresistance with increasing potential strength unveil the important role of anisotropic relaxation processes in strongly modulated electron systems