Thin-film magnetic head flare angle design for pole erasure suppression
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Solution Overview
Problem
Conventional thin-film magnetic heads face challenges in efficiently narrowing magnetic flux to the leading end of the main magnetic pole layer, leading to reduced magnetic recording capability and increased pole erasure (PE), due to uncontrolled yoke form and magnetization anisotropy.
Innovation Solution
A thin-film magnetic head design featuring a main magnetic pole layer with stepwise narrowing flare parts and an auxiliary yoke layer, where the first flare part has a smaller angle than the second flare part, and the auxiliary yoke layer's flare angle is between the first and second flare angles, ensuring magnetic flux is effectively guided and reducing additional magnetization at the pole leading end.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the main magnetic pole layer is widened in the track width direction to control domain structure, then pole erasure is suppressed, but magnetic recording capability is reduced
Solution Approach 1:
The main magnetic pole layer is divided into multiple sections along the height direction, each with different width configurations. The pole tip portion has a smaller width for high recording capability, while the pole base portion has a larger width for domain control, segmenting the functional requirements along the height axis
Solution Approach 2:
The patent transitions from controlling domain structure only in the track width direction to utilizing the height direction as an additional dimension. By varying the width of the main magnetic pole layer at different heights, the invention creates a three-dimensional domain control strategy that simultaneously achieves both pole erasure suppression and maintained recording capability
2Productivity
If the flare angle of the flare part is set to 45° to narrow magnetization, then magnetic flux concentration is improved, but yoke domain transfer increases causing pole erasure
Solution Approach 1:
Different flare angles are applied at different locations along the height direction. The lower flare part has a larger flare angle for effective magnetization narrowing and flux concentration, while the upper flare part has a smaller flare angle to reduce yoke domain transfer, creating location-specific optimization
Solution Approach 2:
The patent changes the flare angle parameter along the height direction of the main magnetic pole layer. By making the flare angle variable rather than constant, the invention optimizes both magnetic flux concentration and pole erasure suppression through parameter gradient design
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 design suppresses pole erasure while maintaining magnetic recording capability by forming a laterally striped domain and stepwise converging magnetic fluxes, resulting in reduced effective magnetization at the pole leading end.
Implementation Method 1
When the coil layer is energized, the recording magnetic field is induced between the main magnetic pole layer and return path layer
Implementation Method 2
the recording magnetic field is induced between the main magnetic pole layer and return path layer, perpendicularly enters a hard film of the recording medium from a leading end face of the main magnetic pole layer
Data Source
AI summary
To provide a thin-film magnetic head which suppresses PE while securing magnetic recording capability by controlling a domain of a leading end part of a main magnetic pole layer. The first flare part has a first flare angle smaller than a second flare angle of the second flare part. The second flare angle is smaller than 90°. The auxiliary yoke layer has a flare angle not smaller than the first flare angle but not greater than the second flare angle. The length h from the medium-opposing surface of the pole straight part to the end on the deeper side in the height direction of the first flare part satisfies the following conditional expression: h×Bs<0.000008 [m·T] where Bs is the saturated magnetic flux density of the main magnetic pole layer.