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Enhanced Nucleation of Vortices in Soft Magnetic Materials Prepared by Silica Nanosphere Lithography
Author(s) -
Martin Norbert,
Bigall NadjaCarola,
Mönch Ingolf,
Gemming Thomas,
Eychmüller Alexander,
Mattheis Roland,
Schäfer Rudolf,
Schultz Ludwig,
McCord Jeffrey
Publication year - 2011
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201002140
Subject(s) - materials science , vortex , nucleation , monolayer , condensed matter physics , micromagnetics , lithography , nanotechnology , bevel , nanosphere lithography , micrometer , ferromagnetism , magnetic field , optics , optoelectronics , fabrication , magnetization , physics , mechanics , medicine , structural engineering , alternative medicine , pathology , quantum mechanics , engineering , thermodynamics
Abstract Magnetic vortices show promise as data storage structures, however the vortex formation process imposes a lower limit on the element’s size. In this article a technique is presented, which application increases the probability of nucleating of magnetic vortices in sub‐micrometer sized soft magnetic thin film elements. By tailoring the edge geometry of the elements, the symmetry of their magnetic configuration is broken in a manner which favors vortex nucleation. Micromagnetic simulations are presented, which demonstrate this effect in soft‐magnetic disks with beveled edges. The favored edge geometry is realized by applying nanosphere lithography directly on top of a ferromagnetic thin film material. In this process, the film is masked with a self assembled monolayer of SiO 2 ‐nanospheres and subsequently ion‐etched. The resulting magnetic reversal loops show that in both magnetically isolated as well as in closely packed arrays of beveled disks, vortex formation takes place. The technique presented facilitates the vortex formation even in closely packed and small elements. The lowering of the minimum critical diameter for vortex formation enables a significant increase of data storage density in devices based on magnetic vortices.