Spin-wave focusing induced skyrmion generation

TL;DR

This paper introduces a novel method to generate magnetic skyrmions by focusing spin waves using a specially designed lens in chiral ferromagnets, verified through simulations and relevant for spintronic device development.

Contribution

The paper presents a new spin-wave focusing technique to generate skyrmions, combining theoretical design and micromagnetic simulations, advancing skyrmionics and magnonics integration.

Findings

Skyrmions form near the spin-wave focus point with enhanced intensity.

A magnetic droplet initially forms and converts into a skyrmion.

Phase diagram for skyrmion generation based on excitation parameters.

Abstract

We propose a new method to generate magnetic skyrmions through spin-wave focusing in chiral ferromagnets.A lens is constructed to focus spin waves by a curved interface between two ferromagnetic thin films with different perpendicular magnetic anisotropies. Based on the principle of identical magnonic path length, we derive the lens contour that can be either elliptical or hyperbolical depending on the magnon refractive index. Micromagnetic simulations are performed to verify the theoretical design. It is found that under proper condition magnetic skyrmions emerge near the focus point of the lens where the spin-wave intensity has been significantly enhanced. A close investigation shows that a magnetic droplet first forms and then converts to the skyrmion accompanying with a change of topological charge. Phase diagram about the amplitude and duration-time of the exciting field for skyrmion generation is obtained. Our findings would be helpful for designing novel spintronic devices combining the advantages of skyrmionics and magnonics.