Current- and field-driven magnetic antivortices

TL;DR

This paper investigates the dynamics of magnetic antivortices in ferromagnetic thin films, showing they gyrate on elliptical orbits under excitation, with phase behavior depending on excitation type and antivortex polarization, revealing ways to distinguish excitation mechanisms.

Contribution

The study introduces micromagnetic simulations of antivortex gyration, analyzing phase relationships and amplitude modulation under combined excitations, providing new insights into antivortex dynamics and excitation mechanisms.

Findings

Antivortices gyrate on elliptical orbits under excitation.

Phase depends on excitation type and antivortex polarization.

Amplitude can be enhanced or suppressed by combined excitations.

Abstract

Antivortices in ferromagnetic thin-film elements are in-plane magnetization configurations with a core pointing perpendicular to the plane. By using micromagnetic simulations, we find that magnetic antivortices gyrate on elliptical orbits similar to magnetic vortices when they are excited by alternating magnetic fields or by spin-polarized currents. The phase between high-frequency excitation and antivortex gyration is investigated. In case of excitation by spin-polarized currents the phase is determined by the polarization of the antivortex, while for excitation by magnetic fields the phase depends on the polarization as well as on the in-plane magnetization. Simultaneous excitation by a current and a magnetic field can lead to a maximum enhancement or to an entire suppression of the amplitude of the core gyration, depending on the angle between excitation and in-plane magnetization. This variation of the amplitude can be used to experimentally distinguish between spin-torque and Oersted-field driven motion of an antivortex core.