Micromagnetic study of anisotropy sources in textured longitudinal media

Micromagnetic simulations were performed to determine the effects of three anisotropy sources on the orientation ratio (OR) in circumferentially-textured longitudinal recording media. Models of the Co c-axis distribution, disruption of the magnetic coupling due to the texture lines, and stress anisotropy were used to generate hysteresis loops in both parallel and perpendicular directions. Parameters were obtained from experimental measurements. Of these three anisotropy sources, a preferential alignment of the Co c-axis along the grooves produces the largest OR; disruption of the magnetic coupling yields a smaller OR value, but leads to the perpendicular loop closing outside the parallel loop. Although the stress anisotropy increases the coercivity in both directions, the OR is the smallest. A combination of these three anisotropy sources, as well as a weak intergranular exchange, leads to agreement with the experimental measurement of OR.