Anomalous Transport Due To Retroreflection

The magnetotransport of an electron gas in a two-dimensional, random arrangement of overlapping retroreflective crosses is studied using a combination of experiment and classical event-driven molecular dynamics simulation. The experimentally measured magnetoconductivity sigma(xx), as a function of the magnetic field B displays an anomalous behavior at low B fields, accompanied with an increase of sigma(xx), with increasing temperature at B = 0. The simulations show that at B = 0 the magnetoconductivity does not exist and is associated with anomalous diffusion in the asymptotic long-time limit that depends on the orientational order of the obstacles. At any finite B field, the motion of the tracer particle is asymptotically diffusive but the diffusion coefficient vanishes with a power law in the limit B -> 0.