Lijie Guan

Micromagnetic simulation of various pole-tip design perpendicular magnetic recording heads

We have studied the magnetization configuration of various pole-tip design perpendicular magnetic recording heads by using finite element method (FEM) based micromagnetic simulation. Taper pole has larger head field of 13%–25% than nontaper pole and delivers better gradient because the magnetization of the main pole becomes more perpendicular to the air bearing surface (ABS) and an increase in magnetic charge is observed not only at the ABS but also at the slope region. Side shield has less fringing field in the cross-track direction but the field profile is not as simple as the conventional FEM result. The side shield has a complex domain configuration around the edge, which is difficult to switch in polarity via write current excitation, differing from the trailing-shield situation. The magnetic charge of the side-shield wall induces off-track peaks of the fringing field, and so it must be minimized to optimize the side-shield structure.

A Trailing Shield Perpendicular Writer Design With Tapered Write Gap for High Density Recording

With the continuous push for high areal density, the conventional trailing shield perpendicular writer design faces an increasing challenge in maintaining sufficient writability while scaling down the dimensions of the write pole and the shield. In this work, we investigate an improved trailing shield design with the tapered write gap (TWG). It has been found that the TWG design has two unique recording characteristics that enable better extendibility: 1) flux concentration and 2) self-compensation. Both modeling and experimental results show that the TWG design has superior dynamic performance (DP) than conventional trailing shield design, while the sigma of DP parameters induced by the wafer/back-end variations is reduced.

Micromagnetics and Eddy Current Effects in Magnetic Recording Heads

We developed a micromagnetic modeling program for magnetic recording head analysis, taking eddy current effects into account, and studied the 1-GHz high-frequency response. When gyromagnetic precession is dominant with a small damping parameter of 0.01, the eddy current field causes the delay of the response, but the head field intensity increases a lot, compared to the no eddy current case, because the eddy current field cancels the precessional motion and improves the magnetization alignment. Since magnetic soft films have an intrinsic small damping, low-resistivity material is preferable for high-end magnetic recording heads

A Study of Media Dependence of Trailing Shield Perpendicular Write Head

The performance of two types of trailing shield perpendicular writers with either double coil or single coil are investigated. It has been found that signal-to-noise ratio (SNR) performance of different designs strongly depends on the tradeoff of field gradient and writability. Reverse DC noise analysis is used to understand the recording properties of head and media quantitatively. To realize the performance advantages of the single coil design and to suppress the trailing shield erasure, a novel single coil structure with double write gap is proposed.