Perpendicular Magnetic Head Shield Segmentation for Side Erase
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Solution Overview
Problem
Conventional perpendicular recording thin-film magnetic heads with side shields fail to fully absorb magnetic fluxes emitted from the main magnetic pole, leading to insufficient suppression of side erase, which hampers high recording density in magnetic recording media.
Innovation Solution
A perpendicular recording thin-film magnetic head design featuring a main magnetic pole with a tip and base part, a return yoke, and a magnetic shield layer that extends along the side faces of the main magnetic pole, with a nonmagnetic layer between the main magnetic pole and the shield layer, effectively absorbing magnetic fluxes emitted from the side faces to prevent side erase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the throat height is made smaller to increase recording density, then the distance from the side faces of the base part to the magnetic recording medium becomes shorter, but this makes it more difficult for the side shield to fully absorb the magnetic fluxes emitted from the side faces of the main magnetic pole, whereby the occurrence of side erase is hard to suppress sufficiently
Solution Approach 1:
The magnetic shield is divided into two distinct parts: a side shield extending along the medium-opposing surface to hold the tip part, and a base shield extending along the side faces of the base part. This segmentation allows each part to address specific flux emission problems from different regions of the main magnetic pole, enabling effective side erase suppression even with reduced throat height.
Solution Approach 2:
The magnetic shield structure is extended into the height direction by adding a base shield component that runs along the side faces of the base part from the medium-opposing surface downward. This vertical extension creates an additional dimensional barrier that intercepts flux emitted from the base part side faces, compensating for the reduced horizontal distance caused by smaller throat height.
2Object-affected harmful factors
If conventional side shields are used to suppress side erase, then magnetic fluxes emitted toward adjacent tracks are absorbed, but they fail to fully absorb the magnetic fluxes emitted from the main magnetic pole, leading to insufficient side erase suppression
Solution Approach 1:
The magnetic shield is segmented into a side shield and a base shield component, with the base shield specifically positioned to intercept flux from the base part side faces. This segmentation ensures comprehensive coverage of all flux emission sources, eliminating the incomplete absorption problem of conventional single-structure side shields.
Solution Approach 2:
Different portions of the magnetic shield are optimized for specific functions: the side shield handles flux from the tip part while the base shield handles flux from the base part. This local specialization ensures that each region of the shield effectively absorbs flux from its corresponding source region, achieving complete flux absorption.
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 significantly reduces magnetic fluxes reaching adjacent tracks, thereby effectively suppressing side erase and enhancing recording density in magnetic recording media.
Implementation Method 1
The main magnetic pole has a sharpened tip part exposed at the medium-opposing surface and a base part which is wider than the tip part. Since the magnetic flux pumped by a coil layer so as to pass through the base part is concentrated at the tip part of the main magnetic pole, the main magnetic pole can emit a strong magnetic flux toward the magnetic recording medium.
Implementation Method 2
The side shield absorbs, among magnetic fluxes emitted from the main magnetic pole, those emitted toward tracks adjacent to the track to be recorded, so as to restrain the side erase from occurring
Implementation Method 3
The magnetic flux emitted from the main magnetic pole passes perpendicularly through the recording layer so as to be drawn to a soft magnetic backing layer under the recording layer of the magnetic recording medium, thereby magnetizing the recording layer perpendicularly.
Implementation Method 4
a main magnetic pole adjacent magnetic shield layer extending along at least part of side faces of the main magnetic pole other than the medium-opposing surface as seen in a laminating direction, while holding a nonmagnetic layer between the main magnetic pole and the main magnetic pole adjacent magnetic shield layer
Data Source
AI summary
A perpendicular recording thin-film magnetic head comprises a main magnetic pole having a tip main magnetic pole part extending in a height direction from a medium-opposing surface and a base main magnetic pole part connected to the tip main magnetic pole part on a side opposite from the medium-opposing surface side and wider than the tip main magnetic pole part in a track width direction; a return yoke extending in the height direction from the medium-opposing surface and magnetically coupling with the base main magnetic pole part at a position distanced from the medium-opposing surface in the height direction, while opposing the tip main magnetic pole part through a write gap layer in a bit length direction in the medium-opposing surface; and a main magnetic pole adjacent magnetic shield layer extending along at least part of side faces of the main magnetic pole other than the medium-opposing surface as seen in a laminating direction, while holding a nonmagnetic layer between the main magnetic pole and the main magnetic pole adjacent magnetic shield layer.