Perpendicular Magnetic Recording Head Return Yoke Design
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Solution Overview
Problem
Perpendicular magnetic recording heads face issues with Pole Tip Protrusion (PTP) and reduced recording ability due to thermal expansion differences, leading to magnetic saturation and data erasure, which existing technologies fail to adequately address.
Innovation Solution
A perpendicular magnetic recording head design featuring a return yoke layer with a protrusion portion having a maximum width larger than the main magnetic pole layer, and opposed end portions with smaller film thickness, along with a nonmagnetic layer and insulating layer configuration to manage magnetic flux and prevent saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the thickness of the return yoke layer is thinned to suppress PTP, then PTP is suppressed, but the return hole of magnetic flux becomes smaller and recording ability is reduced
Solution Approach 1:
The return yoke layer is designed with non-uniform thickness: a first region with smaller thickness to suppress PTP at the edges, and a second region with larger thickness to maintain sufficient magnetic flux return area. This local differentiation allows simultaneous achievement of PTP suppression and recording ability maintenance.
Solution Approach 2:
The return yoke layer is segmented into multiple regions with different thickness characteristics. The first region (edge portions) has reduced thickness while the second region (central portion) maintains larger thickness, creating a segmented structure that addresses different functional requirements in different areas.
2Stability of the object's composition
If the area of the return yoke layer exposed to the opposed surface becomes smaller, then PTP is suppressed, but the magnetic flux return hole becomes smaller and the vicinity easily reaches magnetic saturation
Solution Approach 1:
The return yoke layer exhibits local quality variation in thickness across different regions. The first region has smaller thickness reducing PTP, while the second region has larger thickness providing adequate magnetic flux return path, preventing magnetic saturation in different areas simultaneously.
3Reliability
If a convex portion is provided in the return yoke layer toward the main magnetic pole layer, then the curvature of magnetization reversal form is remedied, but the convex portion reaches magnetic saturation easily and magnetic flux leaks causing data erasure
Solution Approach 1:
The harmful convex portion that causes magnetic saturation and flux leakage is removed from the return yoke layer design. Instead, a planarized surface is maintained while achieving the desired magnetization reversal form through other means, eliminating the source of magnetic flux leakage and saturation problems.
Solution Approach 2:
The planarized surface design converts the potential harm of a flat return yoke layer (which might seem to reduce magnetic flux return capability) into a benefit by preventing magnetic saturation and flux leakage, while still achieving proper magnetization reversal through the controlled thickness distribution in different regions.
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 design effectively suppresses PTP and enhances recording ability by dispersing magnetic flux and preventing magnetic saturation, while maintaining data integrity.
Implementation Method 1
a coil layer for applying a recording magnetic field to the first magnetic layer and the return yoke layer
Implementation Method 2
the magnetic flux returns to the return yoke layer after passing through the recording medium
Implementation Method 3
the return yoke layer, occupying a formation region still larger than other parts, easily is projected from the opposed surface. This is due to the difference in a thermal expansion coefficient from an insulating material in the vicinity of the return yoke layer
Data Source
AI summary
Particularly, there is provided a perpendicular magnetic recording head capable of suppressing PTP and obtaining a stabilized recording ability by improving the shape of the opposed surface of a return yoke layer and a method of manufacturing the same. The shape of the return yoke layer on the opposed surface includes a downside formed linearly parallel to a track width direction (X direction shown in the drawing), a center portion where a protrusion portion having a maximum width T1 larger than a track width Tw by protruding upwardly is formed in a position opposed to a main magnetic pole layer in a film thickness direction (Z direction shown in the drawing), and opposed end portions, having a film thickness smaller than the center portion, that extend on the opposite sides in the track width direction of the center portion. As a result, it is possible to properly obtain both effects such as the improvement of the recording ability and the suppressing of PTP generation.