Strain Anisotropy and Magnetic Domains in Embedded Nanomagnets

Nanoscale modifications of strain and magnetic anisotropy can open pathways to engineering magnetic domains for device applications. A periodic magnetic domain structure can be stabilized in sub‐200 nm wide linear as well as curved magnets, embedded within a flat non‐ferromagnetic thin film. The nan...

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Bibliographic Details
Published in:Small (Weinheim an der Bergstrasse, Germany) Germany), 2019-12, Vol.15 (52), p.e1904738-n/a
Main Authors: Nord, Magnus, Semisalova, Anna, Kákay, Attila, Hlawacek, Gregor, MacLaren, Ian, Liersch, Vico, Volkov, Oleksii M., Makarov, Denys, Paterson, Gary W., Potzger, Kay, Lindner, Jürgen, Fassbender, Jürgen, McGrouther, Damien, Bali, Rantej
Format: Article
Language:English
Subjects:
Anisotropy
curved magnets
embedded nanomagnets
Ferromagnetic materials
Ferrous alloys
Ion beams
ion‐induced patterning
Magnetic anisotropy
Magnetic domains
Magnets
Nanotechnology
strain anisotropy
Thin films
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Summary:Nanoscale modifications of strain and magnetic anisotropy can open pathways to engineering magnetic domains for device applications. A periodic magnetic domain structure can be stabilized in sub‐200 nm wide linear as well as curved magnets, embedded within a flat non‐ferromagnetic thin film. The nanomagnets are produced within a non‐ferromagnetic B2‐ordered Fe60Al40 thin film, where local irradiation by a focused ion beam causes the formation of disordered and strongly ferromagnetic regions of A2 Fe60Al40. An anisotropic lattice relaxation is observed, such that the in‐plane lattice parameter is larger when measured parallel to the magnet short‐axis as compared to its length. This in‐plane structural anisotropy manifests a magnetic anisotropy contribution, generating an easy‐axis parallel to the short axis. The competing effect of the strain and shape anisotropies stabilizes a periodic domain pattern in linear as well as spiral nanomagnets, providing a versatile and geometrically controllable path to engineering the strain and thereby the magnetic anisotropy at the nanoscale. Nanomagnets of desired geometries can be embedded within non‐ferromagnetic B2 Fe60Al40 templates by locally inducing disorder using a focused Ne+‐ion beam. Penetrating ions cause site‐swapping between Fe and Al atoms as well as a lattice expansion. The lattice expansion is larger along the narrower dimension of the nanomagnet, giving rise to a magnetic anisotropy that manifests periodic magnetic domains.
ISSN:1613-6810
1613-6829
DOI:10.1002/smll.201904738