Write performance of shielded pole heads on media with thin soft underlayers

Abstract

Nonlinear finite element calculations show that the soft underlayer thickness in perpendicular media can be greatly reduced without significant loss of effective switching field strength by using a shielded pole writer in place of the more conventional monopole geometry. In addition, use of a thin soft underlayer (SUL) with a shielded pole writer with a thin SUL results in a higher gradient and a narrower magnetic write width. These results have been qualitatively confirmed experimentally.

The transition from longitudinal to perpendicular recording

“…As rule of thumb, the gap g should be about the same has the head-to-keeper spacing h KS [43]. Practical implementations and theoretical aspects of shielded heads have been discussed in [40,43,[45][46][47][48][49]. Since some of the flux generated by the main pole is sucked away by the shield, the SUL can be made somewhat thinner [48].…”

Effect of soft underlayer magnetic anisotropy on perpendicular recording process

“…Since the magnetic flux from the write pole return to the shielded pole, which is less than 100 nm apart, the writing field is essentially tilted [3]. And since most of the magnetic flux return directly to the shielded return pole, the field duplication effect of the SUL is greatly reduced [4]. The thickness of the SUL can be reduced to below 50 nm.…”

Comparison of media properties between hard/soft stacked composite and capping layer perpendicular recording media

“…However, H/S stacked media showed experimental results of positive nucleation field (H n ) [9,12] and relatively low negative H n [10] compared to CL media. A more negative value of H n is essential for overcoming adjacent track erasure (ATE) and return field-induced partial erasure (RFPE) [13,14].…”