Anisotropy effects in two-dimensional magnetic superlattices

We have studied the magnetoresistance of magnetic surface superlattices in which arrays of square cobalt dots are deposited on top of a GaAs/AlGaAs heterostructure. For it magnetic field inclined to the normal to the sample, strong commensurability oscillations are seen when the inplane component of the field is parallel to the direction of current flow, but there is no such structure when the in-plane field is rotated through 90 degrees. For a normal field, the commensurability oscillations are weak and out of phase for transport in the different cleavage directions. All these results are in agreement with a recent semi-classical model of transport in 2-dimensional lateral superlattices.