  We study plasmon propagation on a metallic two-dimensional surface partially
coated with a thin film of anomalous-Hall material. The resulting three
regions, separated by two sharp interfaces, are characterised by different Hall
conductivities but identical normal conductivities. A single bound mode is
found, which can localise to either interface and has an asymmetric potential
profile across the region. For propagating modes, we calculate the reflection
and transmission coefficients through the magnetic region. We find Airy
transmission patterns with sharp maxima and minima as a function of the plasmon
incidence angle. The system therefore behaves as a high-quality filter.
