Write field gradient effect on perpendicular recording

Abstract

An effect of the write field gradient on perpendicular recording has been studied by three-dimensional finite-element method and micromagnetic modeling. Two conceptual writer designs were compared: the conventional trailing pole (TP) writer with the main pole serving as the trailing pole and the leading pole (LP) writer, where the main pole operates as the leading pole. Both writers record transitions on double-layer media by the trailing edge of the main pole. The LP writer allows effective control of the write field gradient by positioning the trailing edge adjacent to the write gap. The dependencies of the perpendicular HPERP and longitudinal HLONG components of the write field along with a gradient of the perpendicular component HPERP/dx and write angle on write gap length g and write current IW were computed. The LP writer revealed higher HPERP/dx than the TP writer at g⩽2 μm. The HPERP/dx has a maximum at IW=15–20 mA for both writers and decreases with the current increase. The LP writer exhibited higher HPERP/dx and write angle Θ, as well weaker dependence of these parameters on write current than the TP writer in all ranges of current. Micromagnetic modeling of recorded patterns has shown that the LP writer provides better writeability, and a sharper and less curved transition. Both writers demonstrated the best performance at IW=15–20 mA where HPERP/dx and the write angle have the maximum. Severe transition distortion was observed for the TP writer at IW>30 mA.