Moris Dovek

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.

Write head analysis by using a parallel micromagnetic FEM

We develop a parallel micromagnetic finite-element method (micromagnetic-FEM) to handle a large number of micromagnetic elements and utilize it to analyze full head and media models. When the calculation domain decomposition and the one-one node communication are applied, the program shows four times faster calculation in eight CPU operation, as compared with one CPU calculation. We study head field and media magnetization reversal on the frequency of 714 MHz, using different yoke length heads of 6, 10, and 15/spl mu/m. The shorter yoke head shows faster head field reversal and stronger head field strength, and the recorded media magnetization is also larger. The small damping parameter of the head causes not only smaller head field but also the disorder of the media transition.

Relationship Between Head Design and Media Remanent Magnetization in Perpendicular Magnetic Recording

This paper presents micromagnetic modeling results in a perpendicular magnetic recording, which consists of a single-pole head and double-layered media. To know the inplane head field contribution, the relationship between applied angular field and media remanence is studied, and we propose a perpendicular corresponding field for the head field assessment, which can explain media remanence as well such as the main-pole footprint on the media. The shielded-pole/single-coil head shows the best signal-to-noise ratio but the overwrite performance is somewhat poorer than monopole heads, with a large positive to negative head field, which implies a large field gradient. Although the shielded-pole head has smaller erase bands with straight transitions, it can cause trailing-shield-related erasure by the negative field under the high write current input in the single-coil design

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.

Relationship between head design, pole-tip magnetization, head field, and media magnetization in longitudinal recording

We investigated the relationship between head design, pole-tip magnetization, head field, and media magnetization in longitudinal recording. At first we estimate the effective switching field of current mobile media with isotropic anisotropy, and introduce longitudinal corresponding field for the head field assessment. The smaller perpendicular component or large perpendicular field gradient of the head field at the upper pole improves the transition quality, but the small perpendicular field degrades the overwrite performance. So the ideal head field is large longitudinal and perpendicular field for good overwrite and fast attenuation with the large perpendicular field gradient for the transition quality. Some head designs make it possible to control the ratio of the perpendicular component to the longitudinal head field, by changing the pole-tip magnetization direction. As a project to control it, we discuss the effect of the bottom and upper poles configuration on the transition, overwrite, and adjacent track erasure in longitudinal recording.

Anti-Static Robustness Enhancement and High-Frequency Noise Pickup Immunity by Internal Shunting for Tunneling Magnetoresistive Sensors

Internal shunting is introduced on tunneling magnetoresistive heads to enhance device anti-static robustness and external high-frequency noise pickup immunity. The details of the shunting scheme and the mechanism leading to both anti-static robustness and reduced high-frequency noise pickup are discussed.