Magnetic Head Main Pole Composite Layer Design
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Solution Overview
Problem
Magnetic heads in perpendicular magnetic recording systems face issues with unwanted erasure due to skew, leading to degradation in write characteristics, particularly because the main pole's cross-sectional area near the medium facing surface is reduced during etching, affecting recording density and overwrite properties.
Innovation Solution
The magnetic head incorporates a main pole with a first layer and a second layer, where the second layer is located on a thickness-changing portion of the first layer, and a spin torque oscillator is positioned between the main pole and the trailing shield, with an insulating layer interposed to maintain a larger cross-sectional area and prevent degradation of write characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the main pole is configured with decreasing thickness near the medium facing surface to prevent unwanted erasure, then adjacent track erasure is reduced, but the cross-sectional area becomes too small causing insufficient write characteristics
Solution Approach 1:
The main pole is designed with non-uniform thickness distribution: the first layer has decreasing thickness from the rear end toward the front end (near medium facing surface), while the second layer has increasing thickness from the rear end toward the front end. This creates a composite structure where different regions have different thickness characteristics, allowing the front region to prevent unwanted erasure while the overall structure maintains sufficient cross-sectional area for good write characteristics.
2Object-affected harmful factors
If the main pole cross-sectional area is reduced near the medium facing surface, then skew-induced erasure is minimized, but recording density and overwrite property deteriorate
Solution Approach 1:
The main pole is constructed as a composite structure with two different layers: the first layer (e.g., CoFeB) provides magnetic properties and the second layer (e.g., CoFe) provides structural support and additional magnetic properties. This composite structure allows optimization of both the thickness profile for preventing skew-induced erasure and the overall cross-sectional area for maintaining high recording density and overwrite property.
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 enhances write characteristics by maintaining a larger cross-sectional area near the medium facing surface, reducing unwanted erasure and improving recording density while minimizing the voltage required for the spin torque oscillator, thus extending the magnetic head's lifespan.
Implementation Method 1
a spin torque oscillator that generates a microwave magnetic field
Implementation Method 2
The coil generates a magnetic field corresponding to data to be written on the recording medium
Implementation Method 3
The main pole passes a magnetic flux corresponding to the magnetic field generated by the coil and generates a write magnetic field from the end face
Data Source
AI summary
A magnetic head includes a medium facing surface, a coil, a main pole, and a substrate. The main pole includes a first layer, and a second layer lying on the first layer. The first layer includes a thickness-changing portion whose dimension in a direction perpendicular to a top surface of the substrate decreases with decreasing distance to the medium facing surface. At least part of the second layer is located on the thickness-changing portion.