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Advances in Materials Science and Engineering
Volume 2017, Article ID 3149682, 7 pages
https://doi.org/10.1155/2017/3149682
Research Article

Magnetization Reversal in Ferromagnetic Nanorings of Fourfold Symmetries

1Faculty of Engineering and Mathematics, Bielefeld University of Applied Sciences, Interaktion 1, 33619 Bielefeld, Germany
2Institute of Physics, Center for Science and Education, Silesian University of Technology, Ul. Konarskiego 22B, 44-100 Gliwice, Poland

Correspondence should be addressed to Andrea Ehrmann; ed.dlefeleib-hf@nnamrhe.aerdna

Received 31 January 2017; Revised 4 September 2017; Accepted 18 September 2017; Published 16 October 2017

Academic Editor: Jamal Berakdar

Copyright © 2017 Andrea Ehrmann and Tomasz Blachowicz. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Magnetic nanoparticles offer a broad spectrum of magnetization reversal processes and respective magnetic states, such as onion, horseshoe, or vortex states as well as various states including domain walls. These states can be correlated with stable intermediate states at remanence, enabling new quaternary memory devices storing two bits in one particle. The stability of these intermediated states was tested with respect to shape modifications, variations in the anisotropy axes, and rotations and fluctuations of the external magnetic field. In our micromagnetic simulations, 6 different stable intermediate states were observed at vanishing magnetic field in addition to the remanence state. The angular region of approx. 5°–12° between nanoring and external magnetic field was identified as being most stable with respect to all modifications, with an onion state as technologically best accessible intermediate state to create quaternary memory devices.