PMR Write Pole Flare and Side Shield Layout for Adjacent Track Erasure
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Solution Overview
Problem
Current PMR writers face challenges in achieving high recording density with optimal writability and cross-track field gradient, often trading off between field magnitude and gradient, and suffer from adjacent track erasure and residual magnetic fields.
Innovation Solution
A PMR writer design featuring 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 partial side shields to enhance cross-track field gradient and minimize adjacent track erasure, while maintaining sufficient write field magnitude.
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 and adjacent track erasure increases
Solution Approach 1:
The write pole is divided into multiple sections with different flare angles: a first section with a larger flare angle (45-90 degrees) to enhance write field magnitude, and a second section with a smaller flare angle (0-45 degrees) to reduce adjacent track erasure. This segmentation allows each section to optimize for its specific function while working together to resolve the contradiction between field magnitude and field gradient.
2Force
If a short neck height is used, then write field magnitude is improved, but manufacturing precision deteriorates
Solution Approach 1:
Different sections of the write pole are assigned different geometric properties: the first section has a larger flare angle optimized for field magnitude, while the second section has a smaller flare angle optimized for manufacturing precision. This local differentiation allows the structure to achieve high write field while maintaining manufacturability with standard process tolerances.
3Object-affected harmful factors
If a full side shield structure is used, then cross-track field gradient is improved, but write field magnitude deteriorates
Solution Approach 1:
The side shields are positioned to provide magnetic shielding specifically in the cross-track direction where fringe field suppression is needed, while leaving the down-track field path relatively open to maintain write field magnitude. This localized shielding approach addresses the field gradient issue without significantly compromising the write field.
Solution Approach 2:
The side shields are configured with asymmetric positioning and dimensions relative to the write pole, providing stronger shielding effect in the cross-track direction while maintaining better field magnitude in the down-track direction. This asymmetric configuration allows differential control of field gradient and field magnitude.
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
The design improves writability and reduces adjacent track erasure, maintaining high recording density and minimizing pole erasure, with the shield structure effectively managing magnetic flux to prevent unwanted writing.
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 shield structure including a trailing shield and a side shield that may have various configurations... to limit the excessive fringe field onto the adjacent track
Implementation Method 3
the second write pole section has a first side that flares outward at an angle θ between 45 and 90 degrees from a first side of the narrow section, and a second side that flares outward at an angle θ from a second side of the narrow section
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.