For the first time, three-dimensional hysteretic phenomena for a material of moderate coercivity are accurately predicted with use of only microstructural properties as input. The theory includes magnetostatic, crystalline anisotropic, and exchange interactions as suggested by the granular structure. It is found that switching occurs by coherent rotation of individual grains for fields along the perpendicular direction and domain-wall propagation for fields along a longitudinal direction.

• Received 12 November 1986

DOI:https://doi.org/10.1103/PhysRevLett.58.1788