Spintronic devices rely on the precise manipulation of local magnetization. We observe by electron microscopy the response of magnetic domains, walls and vortices of thin magnetite microstructures to external magnetic fields.

 Devices for spintronic applications rely on the precise manipulation of local magnetization. In recent years, magnetic domain walls and vortices have emerged as promising candidates for information carriers in micro- and nanoscale thin film structures, exhibiting superior performance compared to existing devices. For example, magnetic vortex cores have been proposed as memory components, using the bistability of core polarity for binary data storage. In this work, we report on the response of magnetic domains in thin magnetite microstructures to weak external magnetic fields. Magnetite islands were grown by high-temperature oxygen-assisted molecular beam epitaxy on Ru(0001). The islands, micrometric wide and tens of nanometers thick, are of high structural quality, each having grown from a single nucleation center. Their magnetic domain structure is dominated by shape anisotropy, i.e., they present Landau flux-closure domain configurations. The magnetic domains of the in-situ grown microstructures have been imaged directly by means of x-ray magnetic circular dichroism in photoemission electron microscopy while applying external, in-plane magnetic fields along different directions. Upon application of an external field the Landau state vortex core experiences a displacement along a direction perpendicular to the excitation field. The behaviour of the Landau state under the applied magnetic field is quantified and compared with micromagnetic simulations. The results highlight the bulk-like magnetic properties of the nanometer-thick microstructures, opening the way to their possible use in technological applications. A. Mandziak, M.A. Aristu, J.E. Prieto, M. Foerster, L. Aballe, J. de la Figuera, “Motion of magnetic domain walls and vortices in epitaxial magnetite microstructures”, Applied Surface Science 637, 157838 (2023). DOI: 10.1016/j.apsusc.2023.157838.