Spin-wave excitation by spin-polarized current in magnetic nanostructures

A current-driven magnetic point-contact device can support both a quasi-linear propagating spin-wave mode and a nonlinear self-localized evanescent spin-wave bullet mode. In this work we show how the bias field orientation determines the nature of the excited modes. By using a micromagnetic framework we can describe the main properties of the observed modes, deriving also a satisfying agreement with analytical theories. It is also pointed out how the nature of these modes differs in: (i) threshold current of excitation, (ii) precession angle, (iii) frequency spectra, (iv) trajectory of the precessional motion, (v) spatial localization of the spin-wave amplitude.