Excitation of self-localized spin-wave “bullets” by spin-polarized current in in-plane magnetized magnetic nano-contacts: a micromagnetic study

It was shown by micromagnetic simulation that a current-driven in-plane magnetized magnetic nanocontact, besides a quasilinear propagating (“Slonczewski”) spin-wave mode, can also support a nonlinear self-localized spin-wave “bullet” mode that exists in a much wider range of bias currents. The frequency of the bullet mode lies below the spectrum of linear propagating spin waves, which makes this mode evanescent and determines its spatial localization. The threshold current for the excitation of the self-localized bullet is substantially lower than for the linear propagating mode, but finite-amplitude initial perturbations of magnetization are necessary to generate a bullet in our numerical simulations, where thermal fluctuations are neglected. Consequently, in these simulations the hysteretic switching between the propagating and localized spin-wave modes is found when the bias current is varied.