Perpendicular Magnetic Recording Head Pole Layer Segmentation
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Solution Overview
Problem
The existing perpendicular magnetic recording heads face challenges in preventing unintended erasure of information during non-recording due to the magnetic domain structure of the pole layer, which affects the smooth transfer of magnetic flux and leads to residual magnetization leakage.
Innovation Solution
The perpendicular magnetic recording head is designed with a pole layer comprising a first, second, and third portion, where the second and third portions have widths that gradually expand, and the ratio of the third width to the total length of the portions is set to ensure that the magnetization component orthogonal to the recording direction is dominant, preventing unnecessary magnetic flux leakage during non-recording.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the pole layer has a uniform width structure, then the manufacturing process is simple, but residual magnetization leaks from the air bearing surface causing information erasure during non-recording
Solution Approach 1:
The pole layer is divided into three distinct portions (first, second, and third portions) with different width characteristics. The first portion has a narrower width at the air bearing surface, the second portion has an intermediate width, and the third portion has a wider width. This segmentation creates a non-uniform width structure that controls magnetic domain formation, preventing residual magnetization leakage while maintaining manufacturing feasibility through sequential deposition processes.
Solution Approach 2:
Different portions of the pole layer are given different local width characteristics to optimize magnetic flux distribution. The first portion near the air bearing surface has a narrower width to concentrate magnetic flux, the second portion has an intermediate width for transition, and the third portion has a wider width for flux distribution. This local quality variation ensures appropriate magnetic domain structure formation, preventing information erasure during non-recording operations.
2Reliability
If the pole layer width is increased to prevent magnetic flux leakage, then information retention improves, but the recording track width capability is reduced
Solution Approach 1:
The pole layer is segmented into three portions with progressively varying widths. The first portion has a narrower width that determines the recording track width, allowing high-density recording. The second and third portions have progressively wider widths that provide sufficient magnetic path area to prevent residual magnetization leakage. This segmentation enables simultaneous optimization of both recording track width and information retention reliability.
Solution Approach 2:
Different local width characteristics are assigned to different portions of the pole layer. The first portion near the air bearing surface has a narrower width optimized for recording track definition, while the second and third portions have wider widths optimized for preventing magnetic flux leakage. This local quality differentiation resolves the contradiction between track width capability and information retention.
3Productivity
If the pole layer has a narrow width for high recording density, then linear recording density improves, but magnetic flux transfer smoothness deteriorates
Solution Approach 1:
The pole layer is divided into three portions with different width characteristics. The first portion has a narrow width that enables high linear recording density by concentrating magnetic flux. The second and third portions have progressively wider widths that provide sufficient cross-sectional area for smooth magnetic flux transfer. This segmentation allows the narrow first portion to achieve high recording density while the wider second and third portions ensure efficient magnetic flux transfer throughout the pole layer.
Solution Approach 2:
Different local width characteristics are optimized for different functions. The first portion has a narrow width locally optimized for high linear recording density, while the second and third portions have wider widths locally optimized for smooth magnetic flux transfer. This local quality differentiation resolves the contradiction between recording density and flux transfer efficiency.
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 configuration effectively prevents information erasure without intention by ensuring that the magnetic domain structure of the pole layer is appropriate, maintaining the integrity of recorded data during non-recording operations.
Implementation Method 1
when a magnetic flux for recording is generated through passing a current through a thin film coil
Implementation Method 2
a pole layer extending from an air bearing surface to the rear, and guiding the magnetic flux to the recording medium so that the recording medium is magnetized in a direction orthogonal to a surface of the recording medium
Implementation Method 3
the pole layer includes a first pole layer portion, a second pole layer portion, and a third pole layer portion in order from the air bearing surface to the rear, the first pole layer portion having a first width W1 which determines the recording track width of the recording medium, the second pole layer portion having a width which gradually expands from the first width W1 to a second width W2 larger than the first width W1, and the third pole layer portion having a third width W3 larger than the second width W2
Data Source
AI summary
A perpendicular magnetic recording head capable of preventing information erasing without intention at the time of non-recording through making the magnetic domain structure of a pole layer appropriate is provided. A main pole layer is formed so as to include a first pole layer portion having a first width W1 which determines the recording track width of a recording medium and a length L1, a second pole layer portion having a width which gradually expands from the first width W1 to a second width W2 larger than the first width W1 (W2>W1) and a length L2, and a third pole layer portion having a third width W3 larger than the second width W2 (W3>W2) and a length L3. When the ratio W3/(L1+L2+L3) satisfies a relationship of W3/(L1+L2+L3)≧1.0, on the basis of the shape magnetic anisotropy of the main pole layer, the magnetic domain structure of the main pole layer is made appropriate so that an unnecessary magnetic flux is not easily leaked at the time of non-recording.