Giant resonant skew scattering of plasma waves in a two-dimensional electron gas

Electron skew scattering by impurities is one of the major mechanisms behind\nthe anomalous Hall effect in ferromagnetic nanostructures. It is particularly\nstrong at the surface of topological insulators where electron dynamics is\ngoverned by the spin-1/2 Dirac equation. Motivated by recently discovered\nmappings between hydrodynamics and the spin-1 Dirac equation, we consider the\nscattering of plasma waves -- propagating charge density oscillations --\nexcited in graphene off a non-uniform magnetic field created by an adjacent\ncircular micromagnet. The calculated scattering amplitude not only exhibits a\ngiant asymmetry, or skewness, but is resonantly enhanced if the frequency of\nthe incoming wave matches the frequency of the chiral trapped mode circulating\nthe micromagnet in only one direction. Furthermore, if the frequency of the\nincoming plasma wave is a few times larger than the Larmor frequency, the\nangular distribution of its forward scattering is almost indistinguishable from\nthat of a Dirac electron at the surface of a topological insulator scattering\noff a magnetic impurity. The micrometer scale of the proposed setup enables\ndirect investigations of individual skew scattering events previously\ninaccessible in electronic systems.\n