Magnetization process and torque curves in HCP cobalt

Magnetization measurements were made in HCP cobalt by using a very-low-frequency vibrating sample magnetometer in the same external field range where torque curve analyses were performed. The anomalously small value of Ku1 analyzed from the torque curves in the very low field region below 0.3 T was found to be attributable to the appearance of a multiple-domain configuration. If one excludes the multiple-domain configuration range in analyzing observed torque curves, it becomes possible to determine precisely the magnetocrystalline anisotropy constants. The applicability of least-mean-square analysis to unsaturated torque curves is confirmed within the range where the single-domain configuration occurs