Magnetotransport in a random array of antidots

We study the quasiclassical magnetoresistance ρxx(B) of a two-dimensional electron gas scattered by a random ensemble of antidots and, additionally, by a smooth random potential. We demonstrate that the combination of the two types of disorder yields qualitatively new behavior of ρxx(B). In particular, (i) it induces a novel quasiclassical memory effect which leads to a strong negative magnetoresistance, with ρxx(B)∝B−4, followed with increasing B by saturation at a value determined solely by the background smooth disorder; (ii) for larger B, the interplay of drift in smooth inhomogeneities and scattering by antidots gives rise to a “diffusion-controlled percolation”, which yields a positive magnetoresistance and ρxx(B) diverging as a power law in the limit of large B. Experimental relevance to the transport in semiconductor heterostructures is discussed.