Complex free-space magnetic field textures induced by three-dimensional magnetic nanostructures

Donnelly, C. et al. (2022) Complex free-space magnetic field textures induced by three-dimensional magnetic nanostructures. Nature Nanotechnology, 17(2), pp. 136-142. (doi: 10.1038/s41565-021-01027-7) (PMID:34931031)

Abstract

The design of complex, competing effects in magnetic systems—be it via the introduction of nonlinear interactions, or the patterning of three-dimensional geometries—is an emerging route to achieve new functionalities. In particular, through the design of three-dimensional geometries and curvature, intrastructure properties such as anisotropy and chirality, both geometry-induced and intrinsic, can be directly controlled, leading to a host of new physics and functionalities, such as three-dimensional chiral spin states, ultrafast chiral domain wall dynamics and spin textures with new spin topologies. Here, we advance beyond the control of intrastructure properties in three dimensions and tailor the magnetostatic coupling of neighbouring magnetic structures, an interstructure property that allows us to generate complex textures in the magnetic stray field. For this, we harness direct write nanofabrication techniques, creating intertwined nanomagnetic cobalt double helices, where curvature, torsion, chirality and magnetic coupling are jointly exploited. By reconstructing the three-dimensional vectorial magnetic state of the double helices with soft-X-ray magnetic laminography, we identify the presence of a regular array of highly coupled locked domain wall pairs in neighbouring helices. Micromagnetic simulations reveal that the magnetization configuration leads to the formation of an array of complex textures in the magnetic induction, consisting of vortices in the magnetization and antivortices in free space, which together form an effective B field cross-tie wall. The design and creation of complex three-dimensional magnetic field nanotextures opens new possibilities for smart materials, unconventional computing, particle trapping and magnetic imaging.

• Item Type: Articles (Letter)
• Additional Information: Funding: This work was funded by an EPSRC Early Career Fellowship EP/M008517/1 and the Winton Programme for the Physics of Sustainability. This project received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 101001290). C.D. acknowledges funding from the Leverhulme Trust (ECF-2018-016), the Isaac Newton Trust (18-08), the L’Oréal–UNESCO UK and Ireland Fellowship For Women In Science 2019, and the Max Planck Society Lise Meitner Excellence Program. A.H.-R. and S.M. acknowledge support from the European Union’s Horizon 2020 research and innovation programme under Marie Skłodowska-Curie grant H2020-MSCA-IF-2016-746958. A.H.-R. acknowledges funding from the Spanish AEI under project PID2019–104604RB/AEI/10.13039/501100011033. The PolLux end station was financed by the German Bundesministerium für Bildung und Forschung (BMBF) through contracts 05K16WED and 05K19WE2. K.W. acknowledges funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant 701647. Open access funding provided by Max Planck Society.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Hierro Rodriguez, Dr Aurelio and Fernandez-Pacheco, Dr Amalio and McVitie, Professor Stephen and Skoric, Mr Luka and Donnelly, Dr Claire
• Authors: Donnelly, C., Hierro-Rodríguez, A., Abert, C., Witte, K., Skoric, L., Sanz-Hernández, D., Finizio, S., Meng, F., McVitie, S., Raabe, J., Suess, D., Cowburn, R., and Fernandez-Pacheco, A.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Nature Nanotechnology
• Publisher: Nature Research
• ISSN: 1748-3387
• ISSN (Online): 1748-3395
• Published Online: 20 December 2021
• Copyright Holders: Copyright © 2021 The Authors
• First Published: First published in Nature Nanotechnology 17(2): 136-142
• Publisher Policy: Reproduced under a Creative Commons Licence