The effect of underlayer coercivity on the recording characteristics of perpendicular-longitudinal double layered media using ring-type head

The recording of characteristics perpendicular-longitudinal composite double-layered media (CoNiReP perpendicular layer with CoP longitudinal recording underlayer) were examined by using ring-type head. Addition of longitudinal recording underlayer enhanced the reproduced output especially in lower density region. It was considered that such an enhancement was caused not only by superposition of output from perpendicular layer and underlayer, but also by relaxization of demagnetization. Moreover, the reproduced waveform was obtained as a single-peaked pulse regardless of the magneto-motive force, suggesting that the residual magnetization state of the composite medium is the "phase synchronization mode." On the other hand, the reproduced waveform of the composite medium whose underlayer coercivity, Hc(u), was 1200 Oe was observed as di-pulse, indicating the change in the remanent magnetization state due to the variation in the underlayer coercivity. These results suggest that it was able to control the remanent magnetization state of the composite medium by changing the Hc(u), and the possibility of realization of excellent characteristics by optimization of medium parameters of composite media was confirmed.