Thin-Film Magnetic Head Pole Layer Saturation Control
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Solution Overview
Problem
Current thin-film magnetic heads for perpendicular magnetic recording face challenges in reducing jitter and error rates due to curvature issues in the magnetic field contour, which are not adequately addressed by existing designs, leading to limitations in recording density and accuracy.
Innovation Solution
A thin-film magnetic head design featuring a main magnetic pole layer with varying saturation magnetic flux density and a multilayer structure, including auxiliary magnetic pole layers and coil layers, is implemented to control the curvature of the write field contour, ensuring it remains within specific parameters to align with the magnetic sensitivity contour of the MR read head element, thereby reducing jitter and enhancing recording density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional main magnetic pole with trapezoid cross-section is used, then the magnetic field can be generated for writing, but the magnetic field contour has curvature that causes large jitter and increased error rate
Solution Approach 1:
The main magnetic pole is divided into multiple layers (first main magnetic pole layer, second main magnetic pole layer, third main magnetic pole layer) with different saturation magnetic flux densities. The first layer has higher saturation flux density than the second layer, creating localized magnetic field control to reduce contour curvature and jitter.
Solution Approach 2:
The magnetic head uses composite magnetic pole structures with multiple layers of different magnetic materials or compositions. This composite structure enables precise control of the magnetic field distribution to minimize curvature effects and reduce error rates.
2Productivity
If the magnetic field contour curvature is reduced to improve jitter, then recording density can be increased, but the magnetic field strength may be weakened
Solution Approach 1:
Different layers of the main magnetic pole have different saturation magnetic flux densities tailored to specific functional requirements. The first layer provides strong field for writing, while the second layer with lower saturation flux density controls the field contour to reduce curvature, achieving both high recording density and adequate field strength.
Solution Approach 2:
The saturation magnetic flux density parameter is varied across different layers of the magnetic pole structure. This parameter change enables independent optimization of magnetic field strength and contour shape, allowing high recording density without compromising write field strength.
3Device complexity
If a single-layer main magnetic pole is used, then the structure is simple, but the curvature of the magnetic field contour cannot be controlled
Solution Approach 1:
The main magnetic pole is segmented into multiple layers (first, second, and third main magnetic pole layers) with distinct saturation magnetic flux densities. This segmentation provides the degrees of freedom needed to control magnetic field contour curvature while maintaining a relatively simple overall head structure.
Solution Approach 2:
The multi-layer magnetic pole structure uses composite magnetic materials or compositions with different saturation flux densities. This composite approach enables precise control of field contour curvature without significantly increasing device complexity, as each layer can be formed using standard thin-film deposition techniques.
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 controlled curvature of the write field contour significantly decreases the error rate and allows for higher recording density by aligning the write field and magnetic sensitivity contours, resulting in improved signal read accuracy and reduced bit length.
Implementation Method 1
at least one coil layer formed in such a way as to pass through between the main magnetic pole layer and the auxiliary magnetic pole layer for inducing a magnetic flux in the main magnetic pole layer and the auxiliary magnetic pole layer
Data Source
AI summary
A thin-film magnetic head with which an error rate is decreased due to a reduction of a jitter without significant decrease in write field, is provided. The head comprises at least one inductive write head element comprising: a main magnetic pole layer having an inner saturation magnetic flux density varying from both side end surfaces in a track-width direction and a leading end surface, toward a center portion in the track-width direction of a trailing end surface; an auxiliary magnetic pole layer; and at least one coil layer, a curvature width WC of a contour line of a write field adjacent to a trailing edge on an ABS side of the main magnetic pole layer satisfying the following expression: −0.15*WT≦WC<12 where WT is a track width and a unit of WC and WT is nanometer.