Effective Magnus Force on a Magnetic Vortex

Abstract

In classical hydrodynamics, a Magnus force exists between a vortex and the hosting fluid acting transverse to their relative motion. There is a quantum Magnus force acting on vortices in superfluids and superconductors and an analogous force acting on magnetic vortices excited in spin systems. Couplings with the system quasiparticles can modify this to an effective Magnus force by introducing transverse damping forces. The existence and magnitude of transverse damping forces are highly controversial and have not been settled by experiment. We derive the various damping forces on a vortex in a magnetic system, in particular, damping forces acting longitudinally and transversely to current and past motion (memory effects). In a magnetic system, we expect experiments can more accurately study vortex motion for comparison with theory. Despite the simplicity of the spin system, the results are general and should reveal quantitative behaviour for the superfluid/superconductor systems.