Journal Article

FZJ-2015-02600

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Off-axis electron holography of ferromagnetic multilayer nanowires

Akhtari-Zavareh, A. ; Carignan, L. P. ; Yelon, A. ; Ménard, D. ; Kasama, T. ; Herring, R. ; Dunin-Borkowski, R.FZJ* ; McCartney, M. R. ; Kavanagh, K. L.

2014
American Inst. of Physics Melville, NY

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Please use a persistent id in citations: http://hdl.handle.net/2128/16820  doi:10.1063/1.4887488

Abstract: We have used electron holography to investigate the local magnetic behavior of isolated ferromagnetic nanowires (NWs) in their remanent states. The NWs consisted of periodic magnetic layers of soft, high-saturation magnetization CoFeB alloys, and non-magnetic layers of Cu. All NWs were fabricated by pulsed-potential electrodeposition in nanoporous alumina membranes. The NW composition and layer thicknesses were measured using scanning transmission electron microscopy and energy dispersive spectroscopy. The magnetization of individual NWs depended upon the thicknesses of the layers and the direction of an external magnetic field, which had been applied in situ. When the CoFeB was thicker than the diameter (50 nm), magnetization was axial for all external field directions, while thinner layers could be randomized via a perpendicular field. In some cases, magnetization inside the wire was detected at an angle with respect to the axis of the wires. In thinner Cu/CoFeB (<10 nm each) multilayer, magnetic field vortices were detected, associated with opposing magnetization in neighbouring layers. The measured crystallinity, compositions, and layer thicknesses of individual NWs were found to be significantly different from those predicted from calibration growths based on uniform composition NWs. In particular, a significant fraction of Cu (up to 50 at. %) was present in the CoFeB layers such that the measured magnetic induction was lower than expected. These results will be used to better understand previously measured effective anisotropy fields of similar NW arrays.

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Contributing Institute(s):

1. Mikrostrukturforschung (PGI-5)

Research Program(s):

1. 42G - Peter Grünberg-Centre (PG-C) (POF2-42G41) (POF2-42G41)

Appears in the scientific report 2014

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Database coverage:
; ; Current Contents - Physical, Chemical and Earth Sciences ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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