Magnetic interaction among particles in Co–Cr–Ta media and Co/Pt multilayered media evaluated by anomalous Hall effect

A new method for evaluating magnetic interaction among the particles in perpendicular magnetic recording layers under canted magnetic field has been proposed using anomalous Hall effect (AHE) measurement and vibrating sample magnetometer (VSM) measurement. Initial curves and magnetic hysteresis loops were measured to determine ΔM, an evaluation index to estimate interaction using the relation as ΔM=Minit−0.5×(Mup+Mdown). The degree of interaction ΔM can be determined as a vector by combining the results obtained by VSM and AHE measurements. Distribution of vertices (DOV) of ΔM can be regarded as a degree of interaction in a particular direction. The DOV of ΔM in Co–Cr–Ta thin film extended along the in-plane direction and showed gradual convergence as the applied field direction canted toward the film plane. This can be an indication that the magnetic particles in the Co–Cr–Ta thin film tend to incline to the applied field direction individually. On the other hand, the DOV of ΔM in Co/Pt multilayered thin film extended along the perpendicular direction and the shape of the trajectory of ΔM remained unchanged though the applied field direction deviated widely from the normal direction. This may be due to the strong perpendicular anisotropy in the Co/Pt multilayered thin film.