Mechanisms of nonlinear spin-wave emission from a microwave-driven nanocontact

Abstract

We present a micromagnetic study of linear and nonlinear spin-wave modes excited in an extended permalloy thin film by a microwave driven nanocontact. We show that the linear mode having the frequency equal to the excitation frequency ($f$) is driven by the ac Oersted field component perpendicular to the static external field (applied in-plane of the sample). The nonlinear mode with the frequency $f$/2 is excited as an independent eigenmode within a parametric longitudinal pumping process (due ac Oersted field component parallel to the bias field). Spectral positions of those modes are determined both in the space and phase domain. The results are important for the transfer of information coded into spin waves between nanocontacts, and for synchronization of spin transfer torque nano-oscillators.