HMTS-ALIGNED STO WRITE HEAD FOR MAMR RECORDING
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Solution Overview
Problem
Conventional microwave assisted magnetic recording (MAMR) heads with wide high moment trailing shields (HMTS) face reliability issues and stray field problems due to excessive protrusion and magnetic charge, which affect bit per inch (BPI) and write gap corner performance.
Innovation Solution
The design patterns the HMTS together with the spin-torque oscillator (STO) layer, reducing HMTS width to match the main pole, creating a thicker non-magnetic write gap at off-track-center locations, allowing for flexible write gap width and thickness, and simultaneous trimming of HMTS and STO layers to align with the main pole, enhancing reliability and curvature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the HMTS is made much wider than the MP in cross-track dimension to attract MP field to return to the trailing side, then the BPI property is improved, but the HMTS has more protrusion exposing the STO to reliability concerns and induces more magnetic charge causing stronger stray fields
Solution Approach 1:
The patent changes the width parameter of the HMTS from being much wider than the MP to having substantially the same width as the MP in the cross-track dimension. This parameter change reduces the protrusion of the HMTS, thereby protecting the STO from reliability concerns while maintaining adequate BPI performance through optimized field return paths.
2Productivity
If the HMTS is made much wider than the MP in cross-track dimension, then the BPI property is improved, but the HMTS induces more magnetic charge in the write gap corner causing stronger stray fields
Solution Approach 1:
The patent reduces the cross-track width of the HMTS to match the MP width, which decreases the magnetic charge accumulation in the write gap corner and reduces the strength of stray fields generated by the HMTS, while maintaining adequate BPI performance.
3Reliability
If the HMTS width is reduced to match the main pole width, then the protrusion and stray fields are reduced improving reliability, but the field return path to the trailing side may be weakened
Solution Approach 1:
The patent applies local quality by optimizing the HMTS width to match the MP width specifically in the cross-track dimension, creating a localized configuration that reduces protrusion and stray fields while maintaining adequate field return capability through proper positioning and depth of the HMTS.
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 configuration strengthens the write field, improves bit per inch (BPI) performance, and reduces reliability concerns by minimizing HMTS exposure and stray fields, while allowing for flexible write gap dimensions that enhance overwrite and adjacent track interference performance.
Implementation Method 1
the energy barrier that prevents the polarity of a magnetic bit from being reversed by an applied magnetic field is not reduced by optical heating, but rather by supplying the bit with resonant energy from an external oscillating magnetic field produced by an additional element called a spin-torque oscillator (STO)
Implementation Method 2
A high moment trailing shield (HMTS) is used to attract the MP field to return to the trailing side of the MP in order to improve the bits per inch (BPI) property of the writer
Data Source
AI summary
A PMR (perpendicular magnetic recording) write head configured for microwave assisted magnetic recording (MAMR) includes a spin-torque oscillator (STO) and trailing shield formed of high moment magnetic material (HMTS). By patterning the STO and the HMTS in a simultaneous process the HMTS and the STO layer are precisely aligned and have very similar cross-track widths. In addition, the write gap at an off-center location has a thickness that is independent from its center-track thickness and the write gap total width can have a flexible range whose minimum value is the same width as the STO width.