Perpendicular Magnetic Recording Head Shielding for Side Fringing
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Solution Overview
Problem
In perpendicular magnetic recording heads with narrow tracks, side fringing during skewing is difficult to suppress without compromising the recording magnetic field intensity and gradient, as existing methods either fail to absorb leakage magnetic fluxes effectively or reduce the recording magnetic field strength.
Innovation Solution
A magnetic shield layer is provided on the leading edge side of the main magnetic pole layer, comprising a pair of side shield parts and a bottom shield part made of soft magnetic material, positioned to absorb leakage magnetic fluxes without affecting the recording magnetic field, thereby maintaining the recording magnetic field intensity and gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a shield layer is provided surrounding the main magnetic pole layer, then leakage magnetic fluxes are absorbed and side fringing is suppressed, but recording magnetic fluxes are also absorbed and the recording magnetic field intensity becomes extremely small
Solution Approach 1:
The shield layer is divided into a pair of side shield parts and a bottom shield part, with the side shield parts positioned to absorb leakage flux from side faces and the bottom shield part positioned below the leading edge. This segmentation allows selective absorption of harmful leakage flux while preserving the recording magnetic field path to the recording medium.
Solution Approach 2:
The shield layer is provided only on the leading edge side of the main magnetic pole layer, not on the trailing edge side. The side shield parts are positioned at specific locations opposing the side faces of the magnetic pole part. This localized placement ensures that shielding action is applied only where leakage flux occurs, while maintaining recording magnetic field intensity in the essential recording region.
2Object-generated harmful factors
If the main magnetic pole layer is made narrower on the leading edge side to suppress side fringing, then leakage magnetic fields do not reach adjacent tracks, but the main magnetic pole layer fails to keep the size in the thickness direction and exhibits an inverted triangular form
Solution Approach 1:
A nonmagnetic material layer is interposed between the main magnetic pole layer and the shield layer. This intermediary layer provides magnetic isolation, allowing the shield layer to absorb leakage flux without interfering with the magnetic field generation and transmission function of the main magnetic pole layer, thereby maintaining precise track width control.
3Object-generated harmful factors
If a magnetic shield layer is provided on the trailing edge side of the main magnetic pole layer, then leakage magnetic fluxes are absorbed, but magnetic fluxes transmitted to the trailing edge side are also absorbed and the recording magnetic field intensity applied to the recording medium decreases
Solution Approach 1:
Instead of providing the shield layer on the trailing edge side as in conventional approaches, the shield layer is inverted and positioned on the leading edge side of the main magnetic pole layer. This inversion allows the shield to absorb leakage flux before it propagates to adjacent tracks, while the trailing edge remains open to transmit recording magnetic flux to the recording medium without interference.
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 magnetic shield layer effectively suppresses side fringing during skewing by absorbing leakage magnetic fluxes without reducing the recording magnetic field strength, improving the recording magnetic field gradient and maintaining high recording performance even for media with high coercivity.
Implementation Method 1
a magnetic shield layer made of a soft magnetic material is provided on the leading edge side of the magnetic pole part... The magnetic shield layer has a pair of side shield parts separated from each other at the leading edge of the magnetic pole part so as to oppose both side faces in a track width direction of the magnetic pole part, and a bottom shield part magnetically connected to the pair of side shield parts
Implementation Method 2
a coil layer inducing a recording magnetic field between the main magnetic pole layer and return yoke layer upon energization. The recording magnetic field induced between the main magnetic pole layer and return yoke layer perpendicularly enters a hard magnetic film of the recording medium
Data Source
AI summary
In a perpendicular magnetic recording head in which a magnetic pole part of a main magnetic pole layer exposed at a medium-opposing surface exhibits a trapezoidal form narrower at a leading edge than at a trailing edge on the return yoke layer side, a magnetic shield layer having a pair of side shield parts separated at the leading edge so as to oppose both side faces of the magnetic pole part and a bottom shield part magnetically connected to the pair of side shield parts and positioned below the leading edge of the magnetic pole part is provided on the leading edge side in the track width direction of the magnetic pole part of the main magnetic pole layer.