Magnetic Write Head Shield Structure for High Density Recording
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Solution Overview
Problem
In high data density magnetic recording, existing perpendicular magnetic write heads face challenges in minimizing adjacent track interference and maximizing the signal to noise ratio (SNR) due to leakage fields and erasure of data in adjacent tracks.
Innovation Solution
A magnetic write head with a novel wrap-around shield structure featuring a trailing shield and side shields separated by non-magnetic gap layers, including convex bumps at the junctions, which enhances the field gradient and reduces leakage fields to adjacent tracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional write head structure is used, then the device complexity is low, but the signal to noise ratio is poor and adjacent track interference is high
Solution Approach 1:
The shield structure is divided into multiple segments: a trailing shield, side shields, and gap layers. This segmentation allows each component to independently control magnetic flux in specific regions, improving the signal to noise ratio by reducing adjacent track interference while maintaining manageable structural complexity through modular design
Solution Approach 2:
Different regions of the shield structure have different properties: the trailing shield is positioned to control flux at the trailing edge, side shields control lateral flux, and gap layers provide controlled non-magnetic separation. This local differentiation optimizes magnetic flux distribution to improve SNR without requiring uniform complex structures throughout
2Reliability
If the magnetic flux is spread out, then the erasure of previously recorded bits is reduced, but the field gradient is reduced and adjacent track interference increases
Solution Approach 1:
Non-magnetic gap layers are introduced as intermediary structures between the write pole and shields. These gap layers control and direct magnetic flux paths, preventing flux leakage to adjacent tracks while maintaining sufficient field gradient at the write interface. The gaps act as mediators that balance flux concentration and isolation
3Object-generated harmful factors
If the shield is positioned closer to the write pole, then the leakage fields are reduced, but the gap layers become thinner and manufacturing precision requirements increase
Solution Approach 1:
The gap layers are designed with sufficient thickness to effectively control leakage fields without requiring ultra-precise manufacturing. By using partial gap coverage and strategic positioning of shield structures, the design achieves adequate flux control with tolerances that are manufacturable using conventional techniques, avoiding the need for excessively thin gaps that would demand extreme precision
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 solution improves the signal to noise ratio and reduces adjacent track interference by concentrating the magnetic flux closer to the trailing edge of the write pole, resulting in increased field gradient and reduced negative fields, thereby enhancing recording performance in high data density disk drives.
Implementation Method 1
The non-magnetic trailing gap layer extends laterally beyond the first and second sides of the write pole and laterally beyond the non-magnetic side gap layer
Implementation Method 2
the magnetic shield has first and second convex bumps each of the convex bumps being located at a junction between one of the non-magnetic side gap layers and the trailing gap layer
Implementation Method 3
An electrically conductive write coil induces a magnetic flux through the write coil. This results in a magnetic write field being emitted toward the adjacent magnetic medium
Implementation Method 4
The magnetization of the pinned layer is typically pinned by exchange coupling with an antiferromagnetic layer. When the magnetizations of the pinned and free layers are parallel with respect to one another, scattering is minimal and when the magnetizations of the pinned and free layer are antiparallel, scattering is maximized.
Data Source
AI summary
A magnetic write head having a gap structure that improves write head performance. The write head includes a magnetic write pole and a magnetic shield that is separated from the trailing edge of the write pole by a non-magnetic trailing gap layer and is separated from the sides of the write pole by non-magnetic side gap layers. The trailing gap extends laterally beyond the side gap layers, and a convex bump is formed at an edge of the magnetic shield at a location near the trailing end of each of the side gap layers.