Magnetization configurations in plate‐shaped fine particles of hcp cobalt

In order to find out the magnetization configurations in the plate‐shaped fine particles of hcp colbalt, the energy densities of the particle with various magnetization configurations are calculated as a function of the particle radius r0 for the axial ratio n from 1 to 1/8. It is found that the particle has a single domain structure if r0 is smaller than the critical radius rc, and that rc is 17 nm for n=1/2, 12 nm for n=1/4, and 11 nm for n=1/8. It is also found that the particle with r0 larger than rc has a form of the curling configuration: the spins stand up in the center of the particle, but become the circular configuration in the off‐center region, and that the particle has this curling configuration to r0 of 33 nm for n=1/2 and 200 nm for n=1/4.