Laser-induced real-space topology control of spin wave resonances

TL;DR

This study demonstrates how femtosecond laser pulses can ultrafastly manipulate magnetic spin textures in ferrimagnetic multilayers, enabling control over spin wave resonances and magnetic states.

Contribution

It introduces a method for ultrafast, laser-induced control and transformation of magnetic textures like skyrmions and bubbles in ferrimagnetic multilayers.

Findings

Distinct spin wave dynamics identify different magnetic textures.

Strong laser excitation can create and annihilate skyrmions and bubbles.

Micromagnetic simulations and microscopy confirm texture transformations.

Abstract

Femtosecond laser excitation of materials that exhibit magnetic spin textures promises advanced magnetic control via the generation of ultrafast and non-equilibrium spin dynamics. We explore such possibilities in ferrimagnetic [Fe(0.35 nm)/Gd(0.40 nm)]$_{160}$ multilayers, which host a rich diversity of magnetic textures from stripe domains at low magnetic fields, a dense bubble/skyrmion lattice at intermediate fields, and a single domain state for high magnetic fields. Using femtosecond magneto-optics, we observe distinct coherent spin wave dynamics in response to a weak laser excitation allowing us to unambiguously identify the different magnetic spin textures. Moreover, employing strong laser excitation we show that we achieve versatile control of the coherent spin dynamics via non-equilibrium and ultrafast transformation of magnetic spin textures by both creating and annihilating bubbles/skyrmions. We corroborate our findings by micromagnetic simulations and by Lorentz transmission electron microscopy before and after laser exposure.