Ｒｅｖｅｒｓｅ ＥＣＣ媒体の記録再生及び熱揺らぎ特性

Abstract

Exchange-coupled composite (ECC) media are candidates for achieving recording densities of over 1 Tbpsi. In this study, we investigated the SNR and thermal stability of ECC media, using a micromagnetic simulator. We found that the vertical-exchange (A⊥) interaction between the soft and hard regions greatly influences both the SNR and the thermal stability, but in opposite ways. In other words, a weak A⊥ results in a high thermal stability, while a strong A⊥ increases the SNR. Thus, it is difficult to simultaneously obtain a high SNR and thermal stability using ECC media. To solve this problem, we propose a reverse ECC (RECC) medium in which the positions of the soft and hard regions are reversed with respect to those in conventional ECC media. Under the condition of a weak A⊥ of 5 pJ/m, which is suitable for achieving good thermal stability, RECC media have SNRs that are 7.5 dB higher than those of ECC media at 2000 kfci. This is because the field gradient of the writing field in the hard region of RECC media is considerably improved by closing to the ABS of the writing head. This study demonstrates that it is difficult for conventional ECC media to achieve 1 Tbpsi recording, and shows that RECC media have the possibility of attaining recording densities of over 1 Tbpsi.