MAMR Head Omitting Spin Polarization Layer
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Solution Overview
Problem
Conventional microwave-assisted magnetic recording (MAMR) systems face challenges with signal-to-noise ratio (SNR) due to the presence of a spin polarization layer, which limits the narrowing of the gap between magnetic poles and introduces time delays in magnetization reversal, affecting recording quality and transfer rates.
Innovation Solution
A microwave-assisted magnetic recording head design that omits the spin polarization layer by using a field generation layer (FGL) between the main magnetic pole and the trailing shield, where either a portion of the main magnetic pole or the trailing shield acts as a spin polarization layer, enhancing magnetic field gradient and reducing the gap thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a conventional STO structure with spin polarization layer is used, then magnetization reversal can be achieved, but the gap distance between main magnetic pole and trailing shield cannot be narrowed below the STO film thickness
Solution Approach 1:
The patent extracts and removes the spin polarization layer from the conventional STO structure, retaining only the oscillation layer and trailing shield. This extraction eliminates the thickness constraint that prevented gap narrowing, allowing the gap distance to be reduced to equivalent to or less than the oscillation layer thickness while maintaining STO functionality through alternative spin polarization mechanisms.
Solution Approach 2:
The patent applies local quality by creating a gradient in magnetization orientation within the oscillation layer, where the magnetization direction varies from perpendicular to the film surface at one interface to parallel at another interface. This local variation in magnetic properties enables the oscillation layer to function without a separate spin polarization layer, resolving the contradiction between gap distance and device complexity.
2Measurement precision
If writing magnetic field gradient is increased to produce high SNR, then recording quality improves, but gap distance must be narrowed which becomes problematic with conventional STO structure
Solution Approach 1:
By removing the spin polarization layer, the patent enables gap narrowing to equivalent to or less than the oscillation layer thickness, which allows the writing magnetic field gradient to be increased sufficiently to achieve high signal-to-noise ratio without the structural constraints of conventional STO designs.
3Productivity
If spin polarization layer magnetization is reversed simultaneously with main magnetic pole polarity reversal, then recording can be performed, but time delay occurs until oscillation layer magnetization attains stable oscillation
Solution Approach 1:
The removal of the spin polarization layer eliminates the sequential reversal process. Without this layer, the oscillation layer can attain stable oscillation more quickly after main magnetic pole polarity reversal, reducing the time delay and enabling higher transfer rates.
4Reliability
If dedicated spin polarization layer is used, then magnetization torque can be generated, but recording density and transfer rate are limited
Solution Approach 1:
The patent makes the oscillation layer multi-functional by enabling it to serve both as the oscillating element and as the spin polarization source through its gradient magnetization structure. This eliminates the need for a separate spin polarization layer, allowing increased recording density while maintaining reliable magnetization torque generation.
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 design improves the signal-to-noise ratio and reduces time delays during magnetization reversal, enabling higher recording densities and transfer rates without the need for a dedicated spin polarization layer.
Implementation Method 1
a field generation layer (FGL) adapted to generate a high-frequency magnetic field when current is applied thereto
Implementation Method 2
a main magnetic pole adapted to generate a writing magnetic field when current is applied to a write coil
Implementation Method 3
when an electric current flows to the STO, the electron spin produced by the spin polarization layer has the same orientation as the spin polarization layer. These electrons impart a torque (spin torque) to the magnetization of the oscillation layer
Implementation Method 4
This magnetization rotation of the oscillation layer forms an AC magnetic field which is emitted by the STO
Data Source
AI summary
A microwave-assisted magnetic recording (MAMR) head according to one embodiment includes a main magnetic pole adapted to generate a writing magnetic field when current is applied to a write coil; a trailing shield positioned, at an air bearing surface (ABS), in a trailing direction from the main magnetic pole; and a field generation layer (FGL) positioned, at the ABS, between the main magnetic pole and the trailing shield, wherein either a portion of the main magnetic pole closer to the FGL or a portion of the trailing shield closer to the FGL is adapted to act as a spin polarization layer.