Effect of magnetic anisotropy distribution in longitudinal thin film media

The effects of anisotropy axes distribution on the properties of longitudin al recording media are simulated using the micromagnetic modeling. The angl e between the anisotropy axis and the preferred direction is assumed to fol low the Gaussian distribution. Hysteresis loops are simulated with the fiel d applied in the preferred direction and perpendicular to it. Orientation r atios (OR) are calculated for different anisotropy distribution. OR (coerci vity) increased from 1.4 to 79.2 when standard deviation of anisotropy dist ribution sigma decreased from 0.7 to 0.05. The effect of the anisotropy dis tribution on the recording performance is evaluated, too. The results show that narrowing the anisotropy distribution will increase the OR and decreas e the transition noise power and transition length. It was found that a cri tical point occurred at sigma = 0.15, below which the OR can be maintained at a sufficiently high value and yet the integrated noise power can be kept low. (C) 2000 American Institute of Physics. [S0021-8979(00)15908-0].