Electrical measurement of magnetic-field-impeded polarity switching of a ferromagnetic vortex core

TL;DR

This study demonstrates electrical detection of magnetic vortex core polarity switching in NiFe disks, showing how high-power excitation and core displacement influence the switching dynamics and can impede polarity reversal.

Contribution

It introduces an all-electrical method to observe vortex core polarity switching and reveals how core displacement affects switching behavior through increased stiffness.

Findings

Loss of rectified signal at high powers indicates polarity switching.

Switching frequency range shifts with power, showing non-linear dynamics.

Displacing the core reduces maximum velocity, impeding switching.

Abstract

Vortex core polarity switching in NiFe disks has been evidenced using an all-electrical rectification scheme. Both simulation and experiments yield a consistent loss of the rectified signal when driving the core at high powers near its gyrotropic resonant frequency. The frequency range over which the loss occurs grows and shifts with increasing signal power, consistent with non-linear core dynamics and periodic switching of the core polarity induced by the core attaining its critical velocity. We demonstrate that core polarity switching can be impeded by displacing the core towards the disk's edge where an increased core stiffness reduces the maximum attainable core velocity.