Perpendicular Magnetic Recording Head End Magnetization Control
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Solution Overview
Problem
Conventional perpendicular magnetic recording heads with rectangular return yoke layers suffer from unintentional recording and erasing due to magnetic field concentration at corners, and modifying the return yoke layer to a tilted or curved surface can lead to peeling and chipping issues during polishing and washing.
Innovation Solution
Incorporating end magnetization control layers, specifically antiferromagnetic films with ferromagnetic alloy films, on the return yoke layer to generate an exchange-coupling field that secures the magnetization direction of the end parts to the track width direction, thereby reducing leakage magnetic fluxes and preventing unintentional recording and erasing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the return yoke layer is modified to a tilted or curved surface to prevent magnetic field concentration at corners, then resistance to external magnetic fields is improved, but peeling and chipping occur during polishing and washing processes
Solution Approach 1:
The invention applies different surface characteristics to different regions of the return yoke layer. The front end face is formed with a tilted or curved surface to resist external magnetic fields, while the rear end face is formed with a substantially flat surface to ensure structural integrity during polishing and washing. This local differentiation resolves the contradiction by assigning different functional requirements to different parts of the same component.
Solution Approach 2:
The return yoke layer is segmented into distinct functional zones: a front end face with tilted/curved surface for magnetic field resistance, and a rear end face with flat surface for manufacturing stability. This segmentation allows each zone to be optimized for its specific function without compromising the other, resolving the contradiction between magnetic field resistance and structural integrity.
2Ease of manufacture
If the return yoke layer has a rectangular two-dimensional form, then manufacturing is simple, but magnetic fields concentrate at corners causing unintentional recording and erasing
Solution Approach 1:
The invention introduces asymmetry to the return yoke layer by forming the front end face with a tilted or curved surface instead of a flat rectangular shape. This asymmetric modification redistributes magnetic fields away from corner concentrations, preventing unintentional recording and erasing while maintaining manufacturing feasibility through standard polishing and washing processes.
3Object-generated harmful factors
If a tilted or curved surface is formed on the return yoke layer to prevent magnetic field concentration, then unintentional recording and erasing is suppressed, but the angle of the surface affects peeling and chipping severity
Solution Approach 1:
The invention applies different surface geometries to different regions: the front end face has a tilted or curved surface with optimized angle to prevent magnetic field concentration, while the rear end face has a flat surface to avoid peeling and chipping during polishing. This local quality differentiation resolves the contradiction by matching surface characteristics to functional requirements.
Solution Approach 2:
Instead of making the entire return yoke layer tilted or curved, the invention inverts the approach by keeping the rear end face flat and only modifying the front end face. This inversion strategy prevents peeling and chipping during polishing while still achieving the magnetic field distribution needed to prevent unintentional recording and erasing.
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 solution effectively enhances resistance to external magnetic fields, prevents unintentional recording and erasing, and maintains structural integrity by reducing peeling and chipping risks during processing.
Implementation Method 1
an end magnetization control layer for generating an exchange-coupling field is provided on the upper or lower side of both end parts in a track width direction of the return yoke layer, while the exchange-coupling field fixes magnetization in the end parts to the track width direction
Implementation Method 2
a recording coil which is arranged within the nonmagnetic insulating layer and applies a recording magnetic field to the main magnetic pole layer and return yoke layer
Implementation Method 3
The main magnetic pole layer and return yoke layer are magnetically coupled to each other on the deeper side in the height direction of the medium-opposing surface
Data Source
AI summary
In a perpendicular magnetic recording head comprising a main magnetic pole layer and a return yoke layer which have respective front end faces exposed at a surface opposing a recording medium and are laminated with a nonmagnetic material layer interposed therebetween on the medium-opposing surface, an end magnetization control layer for generating an exchange-coupling field is provided on the upper or lower side of both end parts in a track width direction of the return yoke layer. The exchange-coupling field fixes magnetization in the end parts to the track width direction.