Effects of the rf current and bias field direction on the transition from linear to non-linear gyrotropic dynamics in magnetic vortex structures

TL;DR

This study investigates how rf current and bias field direction influence the transition from linear to nonlinear gyrotropic dynamics in magnetic vortex structures, revealing resonance peak splitting and vortex core polarity switching.

Contribution

It provides a detailed analysis of how rf current amplitude and bias magnetic field orientation control the nonlinear behavior of magnetic vortex dynamics.

Findings

Resonance peak splitting depends on excitation amplitude.

High power excitation causes vortex core polarity switching.

Transition from linear to nonlinear dynamics is controllable via rf current and bias field.

Abstract

We present a frequency-domain study of the dynamic behavior of a magnetic vortex core within a single Permalloy disk by means of electrical detection and micromagnetic simulations. When exciting the vortex core dynamics in a non-linear regime, the lineshape of the rectified dc signal reveals a resonance peak splitting which depends on the excitation amplitude. Using micromagnetic simulations, we show that at high excitation power the peak splitting originates from the nanosecond time scale quasi-periodic switching of the vortex core polarity. Using lock-in detection, the rectified voltage is integrated over a ms time scale, so that the net signal detected between the two resonant peaks for a given range of parameters cancels out. The results are in agreement with the reported effects of the in-plane static field magnitude on the gyration dynamics, and complement them by detailed analysis of the effects of the rf current amplitude and the azimuthal angle of the in-plane bias magnetic field. Systematic characterization shows that a transition from linear to nonlinear dynamical regime can be controlled by rf current as well as by varying the magnitude and the direction of the bias magnetic field.