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 $B\to 0$.

• Received 13 January 2020
• Accepted 9 August 2020

DOI:https://doi.org/10.1103/PhysRevB.102.081302