Method for Measurement of Switching-Field Distribution of Heat-Assisted Magnetic Recording Media

Due to increased emphasis on heat-assisted magnetic recording (HAMR), the characterization of the intrinsic switching-field distribution (iSFD) at elevated media temperatures has become important. In this paper, we introduce an efficient method to measure iSFD based on optical heating and magnetooptic Kerr effect measurement. The major and minor hysteresis loops of perpendicular magnetic recording media and FePt granular media were acquired at different optical heating powers. The optical heating power (or temperature) dependent iSFD of FePt granular media was measured. We observe iSFD broadening of HAMR media at elevated temperatures, which is consistent with theoretical predictions.