Concentric 360° domain wall nesting in magnetic tunnel junction films: a Lorentz TEM study

O'Shea, K., Rode, K., Kurt, H., McGrouther, D. and MacLaren, D.A. (2015) Concentric 360° domain wall nesting in magnetic tunnel junction films: a Lorentz TEM study. Journal of Physics D: Applied Physics, 48(5), 055001. (doi:10.1088/0022-3727/48/5/055001)

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Publisher's URL: http://dx.doi.org/10.1088/0022-3727/48/5/055001

Abstract

We describe the formation of an unusual concentric magnetic domain wall pattern in the free layer of a bottom pinned magnetic tunnel junction. Lorentz microscopy reveals that repeated switching of the free layer with a magnetic field applied perpendicular to the exchange bias direction can produce a series of concentric 360° domain wall loops, a phenomenon we refer to as domain wall nesting. We propose two necessary ingredients for the behaviour: (i) inhomogeneities in the grain-by-grain magnetic dispersion that break local symmetry to produce a preferential sense of magnetic rotation upon field switching; and (ii) structural defects that act to pin 360° domain walls. Further control of this behaviour may provide new functionality for future device applications.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:McGrouther, Dr Damien and O'Shea, Miss Kerry and MacLaren, Dr Donald
Authors: O'Shea, K., Rode, K., Kurt, H., McGrouther, D., and MacLaren, D.A.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Journal of Physics D: Applied Physics
Publisher:Institute of Physics Publishing Ltd.
ISSN:0022-3727
ISSN (Online):1361-6463
Copyright Holders:Copyright © 2015 IOP Publishling
First Published:First published in Journal of Physics D: Applied Physics 48(5):055001
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher.

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
530721Integrating advanced nanomaterials into transformative technologiesDonald MaclarenEngineering & Physical Sciences Research Council (EPSRC)EP/I00419X/1P&A - PHYSICS & ASTRONOMY