Hybrid Material Main Pole for High Frequency Magnetic Recording
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Solution Overview
Problem
High-speed data transfer in hard disk drives (HDDs) is hindered by increasing recording errors as recording frequency increases, due to the limitations of conventional magnetic recording heads in maintaining high data transmission speeds and saturation recording properties.
Innovation Solution
A perpendicular magnetic recording write head with a hybrid material main pole, comprising a high saturation magnetic flux density material at the pole tip and a high magnetic permeability, low saturation magnetic flux density material further away from the air bearing surface, which reduces the ratio of cross-sectional areas in a direction away from the air bearing surface, enhancing field intensity and responsiveness to recording current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional magnetic recording heads are used, then saturation recording properties are maintained, but recording errors increase as recording frequency increases
Solution Approach 1:
The main pole is divided into multiple segments along the track direction, with each segment having different magnetic material properties. The first main pole segment has high saturation magnetic flux density for strong field emission, while the second main pole segment has high magnetic permeability for rapid field response. This segmentation allows the head to maintain both saturation recording properties and high-frequency responsiveness.
Solution Approach 2:
Different regions of the main pole are assigned different material qualities optimized for their specific functions. The pole tip region uses high saturation magnetic flux density material to ensure strong magnetic field emission for reliable recording, while the upper region uses high permeability material to enable rapid magnetic field buildup and response at high frequencies. This local optimization resolves the contradiction between recording reliability and speed.
2Force
If high saturation magnetic flux density material is used throughout the main pole, then strong magnetic field emission is achieved, but magnetic field response speed decreases
Solution Approach 1:
The main pole structure implements local quality differentiation by using high saturation magnetic flux density material at the pole tip for strong field emission, and high permeability material in the upper region for fast field response. This spatial differentiation of material properties resolves the contradiction between magnetic field intensity and response speed.
Solution Approach 2:
The main pole is constructed as a composite structure with two different magnetic materials having complementary properties. The combination of high saturation magnetic flux density material and high permeability material creates a synergistic effect where each material contributes its superior property to the overall pole performance, achieving both strong field emission and rapid response.
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 hybrid material main pole structure improves recording field responsiveness and reduces recording errors, allowing for higher data transmission speeds and increased track density without compromising saturation recording properties.
Implementation Method 1
A strong, highly concentrated magnetic field emits from the write pole in a direction perpendicular to the magnetic disk surface, magnetizing the magnetically hard top layer
Implementation Method 2
The resulting magnetic flux then travels through the soft underlayer, returning to the return pole
Data Source
AI summary
Approaches for a magnetic write head having a hybrid material main pole, in which a first magnetic material has a first cross-sectional area (A1) and a second magnetic material has a second cross-sectional area (A2), and wherein the ratio A1/A2 reduces in a direction away from the air bearing surface. The first material comprises a high saturation magnetic flux density material, and the second material comprises a high magnetic permeability and low saturation magnetic flux density material having a lower saturation magnetic flux density than said first material.