Return Field Induced Partial Erasure in Trailing Edge Shielded Perpendicular Writers

Trailing edge shielded pole head is the primary writer design for perpendicular recording (PMR) with soft under layer (SUL), due to its higher field gradient compared to a single pole head. In this paper, both by modeling and by experiments, with certain combinations of head, media, SUL, and write current, the return field induced partial erasure (RFPE) will occur, causing recording performance degradation was demonstrated. Therefore, head, media and system optimizations are necessary in order to avoid this issue. The finite element modeling results of the on-track Stoner-Wohlfarth field for three write currents are obtained. It can be seen that both the recording field from the main pole (MP) and the return field increase with increasing write current. Micromagnetic write modeling has also been done, which showed written magnetization patterns consistent with the experimental data.