PMR Write Pole Flare Angle With Side Shields for Track Erasure
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Solution Overview
Problem
Current PMR writer designs face challenges in achieving high recording density with narrow track widths, as they struggle to balance write field magnitude and cross-track field gradient, leading to issues with writability and adjacent track erasure, and fail to adequately minimize residual magnetic fields that cause unintended writing.
Innovation Solution
The design incorporates a main write pole layer with a large flare angle and a side shield or semi-side shield configuration, which includes a trailing shield and various side shield structures to enhance cross-track field gradient and writability, while minimizing pole erasure by optimizing the geometry and placement of shields relative to the write pole.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a large flare angle is used in the main write pole, then write field magnitude is improved, but cross-track field gradient deteriorates due to increased fringe field causing adjacent track erasure
Solution Approach 1:
A side shield structure is introduced as an intermediary element between the main write pole and adjacent tracks. The side shield, positioned laterally adjacent to the narrow section of the write pole, acts as a magnetic flux guide that redirects fringe fields away from adjacent tracks while preserving the large flare angle geometry needed for high write field magnitude.
Solution Approach 2:
The side shield is strategically positioned only in specific regions - laterally adjacent to the narrow section of the write pole where fringe fields are most problematic. This localized shielding approach addresses adjacent track erasure in critical zones without interfering with the overall large flare angle geometry and write field generation.
2Object-generated harmful factors
If a full side shield structure is applied to improve cross-track field gradient, then adjacent track erasure is reduced, but write field magnitude drops below minimal performance requirements
Solution Approach 1:
Instead of implementing a full side shield structure that would completely block magnetic flux, a partial side shield is used that provides sufficient shielding against adjacent track erasure while leaving gaps that allow adequate magnetic flux to reach the recording media. The side shield covers only the critical regions where fringe fields cause problems.
Solution Approach 2:
The side shield structure is designed with non-uniform properties - thicker or present in regions where fringe field control is critical, and thinner or absent in regions where write field magnitude is prioritized. This spatially varying shield design balances the competing requirements of reducing adjacent track erasure and maintaining write field strength.
3Quantity of substance
If narrow track width is achieved for high recording density, then areal recording density is improved, but writability deteriorates due to reduced field magnitude
Solution Approach 1:
The write pole is segmented into distinct geometric sections - a narrow section at the air bearing surface that defines the narrow track width for high density, and a wider base section with large flare angle that generates strong write field magnitude. This segmentation allows the pole to simultaneously achieve narrow track width and high field strength.
Solution Approach 2:
The write pole employs asymmetric geometry where the narrow section at the ABS is significantly narrower than the base section. This asymmetric design creates a large flare angle between the sections, concentrating magnetic flux at the narrow pole tip to achieve high field magnitude despite the narrow track width requirement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration improves writability and reduces adjacent track erasure by maintaining sufficient write field magnitude and gradient, while minimizing residual magnetic fields, thus enhancing the performance of PMR writers for high-density recording.
Implementation Method 1
The write pole concentrates magnetic flux so that the magnetic field at the write pole tip at the ABS is high enough to switch magnetizations in the recording media 4
Implementation Method 2
a full side shield writer structure is used to limit the excessive fringe field onto the adjacent track
Implementation Method 3
minimize the amount of pole erasure that occurs when the write pole is comprised of high Bs material
Data Source
AI summary
Improved writability and a reduction in adjacent track erasure are achieved in a PMR writer with a large flare angle of 45 and 90 degrees in the main write pole and a full side shield or partial side shield configuration around the narrow write pole section and write pole tip. A trailing shield is formed above the write pole's top surface and a full or partial side shield section is spaced a certain distance from each side of the write pole. The partial side shield has a thickness less than that of the write pole and a top or bottom surface about coplanar with the pole tip's top or bottom edge, respectively. The partial side shield may include two sections on each side of the write pole wherein the bottom surface of a top section is separated by a certain distance from the top surface of a bottom section.