Micromagnetic states in Fe (001) rectangular epitaxial microstructures: The effect of magnetic anisotropy and aspect ratio

• Published in: Journal of magnetism and magnetic materials 2013-03, Vol.330, p.6-11
• Main Authors: Fomin, L.A., Vinnichenko, V.Yu, Malikov, I.V., Mikhailov, G.M.
• Format: Article
• Language: English
• Subjects: Aspect ratio; Epitaxial microstructure; Epitaxy; Ham; Iron; Magnetic fields; Magnetization; Mathematical analysis; Micromagnetic state; Orientation
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2012.08.001

The magnetic structures of Fe (001) epitaxial rectangular elements 100nm thick, 0.25–4μm wide aspect ratio AR 1:4 and 1:8 oriented along the easy (EAM) and hard (HAM) magnetization axes were studied by magnetic force microscopy and micromagnetic calculations. All the elements of 1μm width and wider are in multi-domain states, which type depends on the AR and orientation with respect to EAM. In the elements oriented parallel to EAM at low AR, a diamond state realizes while at larger AR the fundamental state is of Landau type. In the elements with the orientation parallel to HAM at low AR, a cross-tie state is observed and at larger AR the states are of a concertina or a meander type. As the element sizes decrease, the domain wall width does not virtually undergo any changes and the transition from a multi-domain to a quasi-vortex state proceeds through monotonic increase of the sample volume fraction with a non-collinear magnetization distribution. The quasi-vortex state occurs at the width lower than 0.6μm and depends neither on AR nor on the orientation with respect to EAM. The transition from a quasi-vortex to a quasi-single domain state depends on AR and orientation relatively to EAM. ► Fe (001) epitaxial rectangles 100nm thick, 0.25–4μm wide. ► Parallel to EAM at AR=1:4 a diamond at 1:8 the Landau state. ► Parallel to HAM at 1:4 a cross-tie, at 1:8 a concertina state. ► Transition from a multi-domain to a quasi-vortex state occurs at the width 600nm. ► Transition from a quasi-vortex to a quasi-single domain at 1:8 and the width 0.5μm.