Scaling of Coercivity in a 3d Random Anisotropy Model

Abstract

The random-anisotropy Heisenberg model is numerically studied on lattices containing over ten million spins. The study is focused on hysteresis and metastability due to topological defects, and is relevant to magnetic properties of amorphous and sintered magnets. We are interested in the limit when ferromagnetic correlations extend beyond the size of the grain inside which the magnetic anisotropy axes are correlated. In that limit the coercive field computed numerically roughly scales as the fourth power of the random anisotropy strength and as the sixth power of the grain size. Theoretical arguments are presented that provide an explanation of numerical results. Our findings should be helpful for designing amorphous and nanosintered materials with desired magnetic properties.

Submitted to the Journal of Magnetism and Magnetic Materials. 6 pages, 7 figures

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• Scaling of Static and Dynamical Properties of Random Anisotropy Magnets
• Static and Microwave Properties of Amorphous Magnets Near Saturation
• Energy minima and ordering in ferromagnets with quenched randomness