Ultrafast manipulation of magnetic skyrmions by microwave fields

TL;DR

This paper presents a theoretical study on ultrafast control of magnetic skyrmions using microwave fields, revealing how inertia, topological charge, and polarization influence skyrmion trajectories and dynamics.

Contribution

It introduces a model incorporating skyrmion inertia and analyzes the effects of circularly polarized microwave fields on skyrmion motion, highlighting new control mechanisms.

Findings

Skyrmion trajectories change from smooth spirals to polygonal orbits under continuous microwave driving.

The handedness of the microwave polarization determines attraction or repulsion of skyrmions.

System parameters like damping and microwave frequency control the transition between oscillatory and overdamped regimes.

Abstract

We theoretically investigate the inertial dynamics of magnetic skyrmions driven by circularly polarized microwave-induced inverse Faraday effect (MIFE). By incorporating an inertial mass term into the Thiele equation and analytically deriving the microwave-induced magnetic fields and forces, we demonstrate fundamentally distinct dynamical regimes under continuous-wave (CW) versus pulsed excitation. Skyrmion inertia qualitatively transforms trajectories from smooth spirals to polygonal orbits under continuous driving, while enabling sustained post-pulse gyration that reveals the system's intrinsic relaxation dynamics. The handedness of the trajectory is determined by the topological charge and circularly polarized microwave (CPM) helicity: a left-circularly polarized (LCP) CPM attracts skyrmions toward the beam center, while a right-circularly polarized (RCP) CPM repels them. Systematic parameter analysis reveals how Gilbert damping, the intensity and frequency of CPM, and skyrmion mass control the transition between oscillatory and overdamped dynamical phases. Our work identifies inertia, topological charge, and CPM helicity as essential factors in ultrafast skyrmion manipulation and proposes a novel method for designing topological spin textures.