Narrow High Moment Trailing Shield for MAMR Write Heads
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Solution Overview
Problem
Conventional high moment trailing shields in microwave assisted magnetic recording (MAMR) systems are wider than the main pole and spin-torque oscillator, leading to reliability concerns and increased magnetic charge, causing stronger stray fields and adjacent track interference.
Innovation Solution
A new design for the high moment trailing shield with a similar cross-track width to the main pole and spin-torque oscillator, and a thinner down-track thickness, integrated within a perpendicular magnetic recording writer, reduces protrusion and magnetic coupling, enhancing reliability and reducing adjacent track interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the high moment trailing shield is made wider than the main pole, then the trailing shield can attract more magnetic field lines to improve bits per inch, but the shield protrudes more and exposes the spin-torque oscillator to reliability concerns
Solution Approach 1:
The patent changes the width parameter of the high moment trailing shield to match the main pole width, rather than making it wider. This parameter adjustment reduces the protrusion that exposes the spin-torque oscillator, thereby improving reliability while maintaining acceptable recording density through optimized magnetic field distribution.
2Productivity
If the high moment trailing shield is made wider than the main pole, then the shield can improve bits per inch, but the shield induces more magnetic charge in the write gap corner causing stronger stray fields and adjacent track interference
Solution Approach 1:
The patent adjusts the width parameter of the high moment trailing shield to match the main pole width, which reduces the magnetic charge induction in the write gap corner. This parameter change decreases the generation of stray fields and adjacent track interference, resolving the contradiction between productivity improvement and harmful factor reduction.
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 new design improves reliability and recording density by minimizing stray fields and adjacent track interference, maintaining thermal stability and increasing bits per inch while preserving performance characteristics of prior-art writers.
Implementation Method 1
supplying it with resonant energy from an external oscillating magnetic field produced by an additional layer (actually, a multi-layered element, but is here simply denoted a layer) called a spin-torque oscillator (STO)
Implementation Method 2
A high moment trailing shield (HMTS or, more simply, an HS) is used to attract the MP field back to the trailing side of the MP to improve the bits per inch (BPI) of the recording process
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.