Micromagnetic simulations were performed to determine the effects of three
anisotropy sources on the orientation ratio (OR) in circumferentially-textu
red longitudinal recording media. Models of the Co c-axis distribution, dis
ruption of the magnetic coupling due to the texture lines, and stress aniso
tropy were used to generate hysteresis loops in both parallel and perpendic
ular directions. Parameters were obtained from experimental measurements. O
f these three anisotropy sources, a preferential alignment of the Co c-axis
along the grooves produces the largest OR; disruption of the magnetic coup
ling yields a smaller OR value, but leads to the perpendicular loop closing
outside the parallel loop. Although the stress anisotropy increases the co
ercivity 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.