Magnetic domain structure and magnetization reversal in submicron-scale Co dots

We present a magnetic force microscopy (MFM) analysis of arrays of submicron-scale Co dots fabricated by interference lithography. The dots are thin (180–300 Å) and elliptical in shape. MFM reveals that these structures relax into highly ordered remanent states whose symmetry and configuration are g...

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Bibliographic Details
Published in:Journal of magnetism and magnetic materials 1998-12, Vol.190 (1), p.71-80
Main Authors: Fernandez, A, Gibbons, M.R, Wall, M.A, Cerjan, C.J
Format: Article
Language:English
Subjects:
Applied sciences
Co dots
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Domain effects, magnetization curves, and hysteresis
Domain walls and domain structure
Exact sciences and technology
Magnetic force microscopy
Magnetic properties and materials
Magnetization reversal
Metals. Metallurgy
Micromagnetic simulations
Physics
Remanent states
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Summary:We present a magnetic force microscopy (MFM) analysis of arrays of submicron-scale Co dots fabricated by interference lithography. The dots are thin (180–300 Å) and elliptical in shape. MFM reveals that these structures relax into highly ordered remanent states whose symmetry and configuration are governed by their shape anisotropy. In particular, when the dots are saturated along their long-axis, a uniformly magnetized state persists at remanence. However, when the dots are saturated along their short-axis, they relax into a single-vortex state in which the circulation can have either sign. Both states are characterized by smoothly varying magnetization patterns and a high degree of uniformity across the array. We attribute the ordered behavior of these structures to the film microstructure, which allows the shape anisotropy to dominate over magnetocrystalline anisotropy. By imaging a series of minor-loop remanent states, we show that magnetization reversal in these structures occurs via the nucleation and annihilation of a single vortex. Magnetic hysteresis loop measurements are consistent with these observations and provide additional details. Furthermore, we present the results of micromagnetic simulations, which are in excellent agreement with both the MFM images and the hysteresis loop measurements.
ISSN:0304-8853
DOI:10.1016/S0304-8853(98)00267-4