Effect of the Oersted field on the dynamics of magnetic drop solitons formed at a nanocontact

Abstract

The magnon drop soliton is a non-topological structure formed at a nanocontact, and it is referred to as a dynamic soliton since it is stabilized by uniform precession of the magnetization. Because of magnetization precession there is a time dependent interaction between the magnetization and the magnetic field produced by the nanocontact current (referred to as the Oersted field). At a particular instant of precession the Oersted field forces the soliton off-center, but owing to precession this force will average to zero over one precession period. However, when the soliton orbits the nanocontact center at a period equal to the precession period, this force will become constant forcing the soliton off-center. This lowers the Oersted energy with an increase in the soliton orbital kinetic energy. A balance is attained with the soliton undergoing circular orbital motion about the nanocontact, and the orbit radius is determined by minimization of these energies. Previous low frequency approximations are used semi-analytically obtain these energies as well as the orbit radius.