This paper analyzes two-dimensional features of the magnetic microstructure of longitudinal thin-film media. Several MFM analyses of the magnetic cluster size have been presented, but the two-dimensional features of the clusters are not well understood. In order to determine these features, we focused on the distribution of magnetic poles at the boundaries of magnetic clusters, and quantitatively analyzed it by using two kinds of image processing methods: binarization and thinning methods. The results were as follows: (1) we found that some media showed dependence on the specific direction in the distribution of magnetic poles in the dc-erased state, whose features are closely related to the magnetization fluctuations in transition regions, and (2) media with larger fluctuations in the transition region had larger Nm/S0 values and partial erasure (PE) probabilities.
This paper discusses the properties of a high-frequency carrier-type thin-film magnetic field sensor in a GHz band. Calculations based on bias susceptibility theory and Maxwell’s equation indicated that the properties of the sensor in the GHz band were meinly determined by ferromagnetic resonance. The high-sensitivity area shifted to the high magnetic field side when the carrier frequency was increased. The properties are greatly different from those in megahertz band. Therefore, the high-sensitivity area of the sensor can be selected by using saturation magnetization or an anisotropy field to determine the resonance frequency.