Large amplitude vortex gyration in permalloy/ Bi2Se3 -like heterostructures

We consider the excitation of large amplitude gyrotropic vortex core precession in a permalloy nanodisk by the torques originating from the in-plane microwave current flowing along the interface of the permalloy/Bi2Se3 heterostructures, in which the huge charge-to-spin conversion ratio is observed [A. Mellnik et al., Nature 511, 449 (2014)NATUAS0028-083610.1038/nature13534]. We consider analytically and by micromagnetic modeling the dependence of this excitation on the frequency and magnitude of the microwave current. The analogies of the vortex dynamics and the Landau phase-transition theory are demonstrated. These findings open the possibility to excite gyrotropic vortex motion with the current densities far lower than by any other means.