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Open Access Nano Express

Tailoring magnetic anisotropy gradients by ion bombardment for domain wall positioning in magnetic multilayers with perpendicular anisotropy

Michał Matczak12, Bogdan Szymański1, Piotr Kuświk1*, Maciej Urbaniak1, Feliks Stobiecki12, Zbigniew Kurant3, Andrzej Maziewski3, Daniel Lengemann45 and Arno Ehresmann45

Author Affiliations

1 Institute of Molecular Physics, Polish Academy of Sciences, ul. M. Smoluchowskiego 17, Poznań 60-179, Poland

2 NanoBioMedical Centre, Adam Mickiewicz University, ul. Umultowska 85, Poznań 61-614, Poland

3 Laboratory of Magnetism, Faculty of Physics, University of Białystok, ul. Lipowa 41, Białystok 15-624, Poland

4 Department of Physics, University of Kassel, Heinrich-Plett-Str. 40, Kassel 34132, Germany

5 Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), University of Kassel, Heinrich-Plett-Str. 40, Kassel 34132, Germany

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Nanoscale Research Letters 2014, 9:395  doi:10.1186/1556-276X-9-395

Published: 13 August 2014

Abstract

Graded anisotropy magnetic materials possess a coercive field changing laterally with position. A simple fabrication procedure to produce such an anisotropy gradient in a polycrystalline Au/Co layer system without lateral thickness variation and with perpendicular magnetic anisotropy, prototypical for a large variety of thin film systems, is shown. The procedure uses light-ion bombardment without the use of a mask. Magnetization reversal in this polycrystalline layer system takes place by unidirectional movement of a single domain wall only in regions with larger anisotropies and anisotropy gradients. In this anisotropy/anisotropy gradient regime, the domain wall is oriented perpendicular to the coercive field gradient, and it can be positioned along the gradient by an appropriate magnetic field pulse. For smaller anisotropies/anisotropy gradients, the natural anisotropy fluctuations of the polycrystalline layer system induce magnetization reversal dominated by domain nucleation.

PACS

75.30.Gw; 75.70.Cn; 75.60.Ch

Keywords:
Perpendicular magnetic anisotropy; Ion bombardment; Domain walls