A Study on the Magnetic Microstructure of CoCrTa/Cr Film Media, Using Rotational Hysteresis Loss Analysis

Rotational hysteresis loss analysis was carried out for CoCrTa/Cr thin film media fabricated on glass substrate, to evaluate the influence of the microstructure on the media´s magnetic properties. Hk^grain, defined as the magnetic field at which the rotational hysteresis loss vanishes, remained at almost a constant value of about 4.0 kOe, independent of the values of the coercive force. It is considered that Hk^grain almost corresponds to the magnitude of the uniaxial magnetic anisotropy field of the grains, and that the coercive force is mainly determined by the degree of intergranular magnetic coupling interaction. In all the films examined, Hc was mainly determined by the switching of magnetization, independently of the degree of intergranular coupling. Calculated results suggest a possibility that, in CoCrTa films consisting of large grains, the magnetization in each grain changes direction as a result of incoherent magnetization switching.