Controlling bubble and skyrmion lattice order and dynamics via stripe domain engineering in ferrimagnetic Fe/Gd multilayers

TL;DR

This study demonstrates how in-plane magnetic fields can be used to control the formation and dynamic behavior of bubble and skyrmion lattices in ferrimagnetic Fe/Gd multilayers, enabling precise manipulation of magnetic textures.

Contribution

It introduces a method to control and enhance skyrmion and bubble lattice dynamics through initial domain configuration engineering using in-plane magnetic fields.

Findings

In-plane fields increase the frequency and amplitude of breathing modes.

Application of out-of-plane fields creates dense, near-hexagonal skyrmion lattices.

Enhanced control over magnetic textures on picosecond to nanosecond timescales.

Abstract

Ferrimagnetic Fe/Gd multilayers host maze-like stripe domains that transform into a disordered bubble/skyrmion lattice under out-of-plane magnetic fields at ambient temperature. Femtosecond magneto-optics distinguishes these textures via their distinct coherent breathing dynamics. Crucially, applying a brief in-plane ``set'' magnetic field to the stripe state enhances both frequency and amplitude of the bubble/skyrmion lattice breathing mode. Lorentz transmission electron microscopy, magnetic force microscopy, and micromagnetic simulations reveal that this enhancement arises from field-aligned stripes nucleating a dense, near-hexagonal bubble/skyrmion lattice upon out-of-plane field application, with strong indications for a pure skyrmion lattice. Thus, modifying the initial domain configuration by in-plane fields enables precise control of coherent magnetization dynamics on picosecond to nanosecond timescales and potentially even of topology.