A Hall viscosity for skyrmion via magnon interaction

Abstract: We identify a Hall viscosity term directly from the Dzyaloshinskii-Moriya interaction (DMI), that breaks parity symmetry, in the skyrmion motion of insulating magnets by time-averaging the magnon contribution to all orders. The viscosity term is proportional to the skyrmion charge. Skyrmion Hall angle shows significant dependence on the skyrmion shape and size, the ratio of exchange over DMI parameters, while roughly independent of the Gilbert damping parameter. The Hall angles have the same magnitude for opposite skyrmion charges. We speculate a velocity-dependent Hall viscosity contribution to seek asymmetric Hall angles for the opposite charges.