Film optimization of laminated antiferromagnetically coupled media

Longitudinal media with multiple isolated magnetic layers (laminated media) have been shown to have a significant signal-to-noise ratio (SNR) advantage over conventional media. However, the application of laminated media has been hindered by reduced overwrite and wider magnetic pulsewidth compared to conventional media. Some of the major causes for such degradation in recording properties are poor writing of transition in the magnetic layer farther from the head and an offset in the transition position in the multiple magnetic layers resulting from the decrease in head field magnitude with spacing. We find that the transition writing and transition alignment in the multiple magnetic layers of the laminated antiferromagnetically coupled (AFC) media can be optimized by adjusting the magnetic anisotropy of the relevant magnetic layers to compensate for the reduction of the head field magnitude with spacing. This optimization leads to significant improvements in media recording performance, such as an increase of overwrite, reduction of magnetic pulsewidth, and further increase of SNR. Such adjustment should also be applicable to laminated conventional (non-AFC) media.