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

TL;DR

This study uses micromagnetic simulations to explore how microwave-driven nanocontacts excite linear and nonlinear spin-wave modes in permalloy films, revealing mechanisms relevant for spin-wave communication and oscillator synchronization.

Contribution

It identifies the specific excitation mechanisms of linear and nonlinear spin-wave modes and their spectral characteristics in nanocontact systems.

Findings

Linear mode driven by perpendicular ac Oersted field component.

Nonlinear mode at half the frequency excited via parametric pumping.

Spectral analysis of modes in space and phase domains.

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.