Magnetic Head Side Shield Groove Design for Flux Leakage Control
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Solution Overview
Problem
Magnetic heads for perpendicular magnetic recording systems face challenges in suppressing adjacent track erasing and maintaining write characteristics due to flux leakage and skew issues, which affect recording density and data integrity.
Innovation Solution
A magnetic head design incorporating a pole layer, top shield layer, side shield layer, and gap layers with specific geometries and materials to control magnetic flux and reduce flux leakage, including a side shield layer with a groove accommodating the pole layer and an encasing layer to manage the pole layer's width and orientation, thereby minimizing adjacent track erasing and enhancing write characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a side shield layer is provided to suppress adjacent track erasing, then recording density is improved, but flux leakage to the side shield layer causes degradation of write characteristics
Solution Approach 1:
A nonmagnetic gap layer is introduced as an intermediary between the pole layer and the side shield layer. This gap layer prevents direct magnetic coupling while still allowing the side shield layer to perform its function of suppressing adjacent track erasing. The gap layer acts as a mediator that blocks flux leakage paths to the side shield layer while maintaining the necessary magnetic field distribution for writing operations.
Solution Approach 2:
The shield structure is segmented into a top shield layer and a side shield layer, with the side shield layer further divided into a first side shield layer and a second side shield layer positioned at different heights. This segmentation allows each layer to address specific flux leakage paths independently, with the gap layers providing isolation between segments to prevent unwanted magnetic coupling.
2Reliability
If the pole layer width is reduced to improve write characteristics, then overwrite property is improved, but adjacent track erasing increases due to skew
Solution Approach 1:
The pole layer is designed with asymmetric width characteristics: the width in the medium facing surface direction is smaller than the width in the substrate direction. Specifically, the pole layer has a first width in the medium facing surface direction and a second width in the substrate direction, where the first width is smaller. This asymmetric geometry helps concentrate the magnetic flux more effectively in the writing direction while reducing lateral spread that causes adjacent track erasing during skew conditions.
Solution Approach 2:
The pole layer has different width characteristics in different directions: narrower width in the medium facing surface direction and wider width in the substrate direction. This local quality variation allows the pole layer to optimize flux distribution locally - concentrating flux for better write characteristics while the wider base provides structural stability and flux containment.
3Manufacturing precision
If a shield is provided to prevent magnetic flux from reaching the recording medium, then adjacent track erasing is suppressed, but flux leakage from the shield causes degradation of write characteristics
Solution Approach 1:
Nonmagnetic gap layers are positioned between the pole layer and both the top shield layer and side shield layer. These gap layers serve as intermediaries that prevent direct magnetic coupling between the pole layer and the shield layers, thereby blocking flux leakage paths to the shields while allowing the shields to effectively prevent flux from reaching the recording medium.
Solution Approach 2:
The harmful magnetic coupling between the pole layer and shield layers is extracted and eliminated by introducing nonmagnetic gap layers. The gap layers remove the direct magnetic connection that would otherwise cause flux leakage to the shield layers, while the shield layers continue to perform their protective function against the recording medium.
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 design effectively suppresses adjacent track erasing and improves write characteristics by controlling magnetic flux distribution, ensuring reliable data recording and higher recording density.
Implementation Method 1
a coil for generating a magnetic field corresponding to data to be written on the recording medium
Implementation Method 2
the pole layer allowing a magnetic flux corresponding to the magnetic field generated by the coil to pass and generating a write magnetic field for writing the data on the recording medium
Implementation Method 3
The shield has a function of preventing a magnetic flux from reaching the recording medium, the flux being generated from the end face of the pole layer and expanding in directions except the direction perpendicular to the plane of the recording medium
Implementation Method 4
A gap layer made of a nonmagnetic material is provided between the pole layer and the shield
Data Source
AI summary
A magnetic head includes a side shield layer and an encasing layer. The side shield layer has a first end face located in the medium facing surface, a second end face opposite to the first end face, and a first groove accommodating a portion of a pole layer. The first end face includes two portions located on both sides of an end face of the pole layer that are opposite to each other in a track width direction. The encasing layer is formed of a nonmagnetic material and disposed on a side of the side shield layer opposite to a medium facing surface. The encasing layer has a front end face touching the second end face of the side shield layer, and a second groove accommodating another portion of the pole layer. The distance from the medium facing surface to an arbitrary point on the second end face of the side shield layer decreases with decreasing distance from the arbitrary point to the top surface of a substrate.