Magnetization reversal mechanism evaluated by rotational hysteresis loss analysis for the thin film media

Rotational hysteresis loss analysis has been carried out for CoCrTa, CoNiPt, and CoCrPt thin-film media to evaluate the influence of microstructure on coercive force through the measurement of magnetic anisotropy. In each medium, the magnitudes of H_k^grain defined as a magnetic field where rotational hysteresis loss W_r diminishes remain almost a constant value independently of the values of coercive force. With increasing coercive force, the magnitude of the coercive force gradually becomes smaller than that of the switching field of magnetization H_p evaluated by torque analysis. Through the analysis of H_k^grain and H _p, it is suggested that the coercive force in each examined medium is strongly dependent on the degree of intergranular exchange coupling and/or magnetostatic interactions. While on CoNiPt and CoCrPt media coercive force depends on the rotational hysteresis integral, no correlation between them was observed in CoCrTa films