Angular dependence of the remanence coercivity in magnetic recording media

The angular dependence of remanence coercivity was measured for various advanced particulate (Co-gamma, CrO₂, metal particle, Ba-ferrite) and thin-film (CoCrTa, CoNiPt, CoCr) media including longitudinal, isotropic, and perpendicularly oriented types. The results were corrected by vector magnetometry, and by a simple method based on a conventional single-axis VSM and utilizing only the component Mx of the magnetization along the field to correct for the demagnetizing fields. To simplify the measurements, the authors neglected the component of the demagnetizing field perpendicular to the applied field axis, which can introduce significant errors at angles away from 0° and 90°. It is found that the Mx model provides results in agreement with the vector measurements at 90° for all the media. For other angles, however, the Mx model undercorrects for longitudinally oriented media and overcorrects for perpendicularly oriented media. The implications for recording demagnetization and side-track writing are discussed