Correlation between modulation noise and uniaxial anisotropy in high-coercivity thin film recording media

The author studied the recording and noise characteristics of many different high-coercivity thin-film media and their total magnetic anisotropy measured by a torque magnetometer. A good correlation was found between the in-plane anisotropy and the media noise and pulse width of the media. In the presence of high in-plane anisotropy, magnetization reversal in the transition regions must take place essentially in the plane, resulting in zigzag domains and wider transition lengths. A lower in-plane anisotropy allows for magnetization reversal to proceed in part out of the film plane, reducing the length of the transition regions and zigzag noise. Thus, torque magnetometry is a very useful means of characterizing and optimizing thin-film media