Understanding overwrite for high speed magnetic recording

In this article, we present an experimental study of the overwrite degradation in high speed recording. Recorded hard and easy transitions were directly characterized and correlated to medium speed, write current waveform and media properties. It has been found that, when high medium speed becomes greater than the bubble growth speed, the transition will be recorded when the field gradient is poor, which results in not only large hard transition shift, but also hard transition broadening. Slow field rise time causes further degradation due to the effective slowing down of the bubble growth speed. Write current overshoot can significantly suppress the degradation. Medium coercivity and its time dependence also have shown a direct effect on the overwrite degradation.