Stress-induced modification of gyration dynamics in stacked double-vortex structures studied by micromagnetic simulations

TL;DR

This study uses micromagnetic simulations to explore how stress influences the frequency and behavior of vortex gyration in stacked ferromagnetic layers, revealing controllable dynamics for vortex-based oscillators.

Contribution

It demonstrates how stress-induced magnetoelastic anisotropy can tune vortex gyration frequencies and trajectories, providing a new method for controlling vortex oscillators.

Findings

Stress can induce single-frequency vortex gyration modes.

Magnetoelastic anisotropy affects vortex core trajectories.

Strong magnetostatic coupling enables controllable vortex dynamics.

Abstract

In this paper, using micromagnetic simulations, we investigate the stress-induced frequency tunability of double-vortex nano-oscillators comprising magnetostrictive and non-magnetostrictive ferromagnetic layers separated vertically by a non-magnetic spacer. We show that the the relative orientations of the vortex core polarities $p_{1}$ and $p_{2}$ have a strong impact on the eigen-frequencies of the dynamic modes. When the two vortices with antiparallel polarities have different eigen-frequencies and the magnetostatic coupling between them is sufficiently strong, the stress-induced magnetoelastic anisotropy can lead to the single-frequency gyration mode of the two vortex cores. Additionally, for the case of parallel polarities, we demonstrate that for sufficiently strong magnetostatic coupling, the magnetoelastic anisotropy leads to the coupled vortex gyration in the stochastic regime and to the lateral separation of the vortex core trajectories. These findings offer a fine control over gyration frequencies and trajectories in vortex-based oscillators via adjustable elastic stress, which can be easily generated and tuned electrically, mechanically or optically.