Effects of demagnetization fields on the angular dependence of coercivity of longitudinal thin film media

The angular dependence of the apparent coercivity for coherent rotations and incoherent curling and fanning rotations in high-coercivity longitudinal thin film magnetic recording media is calculated and presented with corrections for demagnetization fields in the direction of the applied field. The model used for representing a thin film is a single particle having a fixed magnitude of saturation magnetization and an in-plane easy axis. A sharp peak is found in the angular dependence of the apparent coercivity for incoherent, but not for coherent, rotations. The peak magnitude of the apparent coercivity calculated in units of the anisotropy field is found to increase with increasing saturation magnetizations for curling but not for fanning. The computations of the angular dependence of the apparent coercivity are compared with measurements on high-coercivity longitudinal thin film magnetic recording media