Guiding-center picture of magnetoresistance oscillations in rectangular superlattices - art. no. 115322

We calculate the magnetoresistivities of a two-dimensional electron gas sub jected to a lateral superlattice (LSL) of rectangular symmetry within the g uiding-center picture, which approximates the classical electron motion as a rapid cyclotron motion around a slowly drifting guiding center. We explic itly evaluate the velocity autocorrelation function along the trajectories of the guiding centers, which are equipotentials of a magnetic-field-depend ent effective LSL potential. The existence of closed equipotentials may lea d to a suppression of the commensurability oscillations, if the mean free p ath and the LSL modulation potential are large enough. We present numerical and analytical results for this suppression, which allow, in contrast to p revious quantum arguments, a classical explanation of similar suppression e ffects observed experimentally on square-symmetric LSL's. Furthermore, for rectangular LSL's of lower symmetry they lead us to predict a strongly anis otropic resistance tensor. with high- and low-resistance directions that ca n be interchanged by tuning the externally applied magnetic field.