Effect of background scattering on the magnetoconductance of two-dimensional Lorentz gases

Abstract

The magnetotransport of two-dimensional Lorentz gases is studied in the presence of two types of additional disorder. We observe that at small magnetic fields, dynamic background potentials cause an increase of the conductivity, while it decreases in response to static background potentials, implemented by a secondary Lorentz gas with large mean free path. At intermediate and large magnetic fields, the effect of the additional disorder is independent of its character but changes sign at a threshold magnetic field. The observed phenomenology is interpreted in terms of the influence the background scattering exerts on classical memory effects, in particular on retroreflection, transient superdiffusive motion and drift along the edges of obstacle clusters.