Magnetic Capping Layer Thickness Gradient for MAMR Head
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Solution Overview
Problem
The miniaturization of magnetic recording bits in HDDs for higher recording densities faces challenges due to thermal instability and the need for strong magnetic fields, which are constrained by the structural characteristics of MAMR head components, particularly the oscillation device and main pole, making it difficult to maintain both thermal stability and write-ability.
Innovation Solution
A magnetic recording head with a main pole generating a magnetic field, an oscillation device producing a high-frequency magnetic field, and a magnetic capping layer with a thickness gradient to preserve the oscillation device's thickness, along with a trailing shield, is designed to enhance recording densities by optimizing the structural configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the recording bit size is reduced to increase recording density, then the recording density increases, but thermal stability deteriorates
Solution Approach 1:
The patent changes the magnetic parameters of the recording medium by using a magnetic recording layer with high coercivity (Hc > 2.0 kOe) and perpendicular magnetic anisotropy. This parameter change allows smaller recording bits to maintain thermal stability by increasing the energy barrier against thermal fluctuations, thus resolving the contradiction between increased recording density and maintained thermal stability.
2Reliability
If a magnetic recording medium with large coercivity is used to compensate thermal instability, then thermal stability improves, but write-ability deteriorates due to insufficient magnetic field from the head
Solution Approach 1:
The patent introduces a spin torque oscillator that generates a time-varying oscillating magnetic field dynamically. This dynamic field, when combined with the DC field from the main pole, creates time-varying total magnetic fields that assist in writing to high coercivity media. The oscillating field reduces the effective coercivity during the writing process, enabling write-ability while maintaining the high coercivity needed for thermal stability.
Solution Approach 2:
The patent uses a composite magnetic field structure combining a DC magnetic field from the main pole and an AC oscillating magnetic field from the spin torque oscillator. This composite field approach allows the system to overcome the high coercivity of the recording medium during writing while maintaining thermal stability through the same high coercivity properties during data storage.
3Force
If the trailing gap is narrowed to increase recording magnetic field, then the recording magnetic field increases, but the oscillation device cannot be properly positioned
Solution Approach 1:
The patent resolves the spatial conflict by transitioning the oscillation device to a different dimensional configuration - placing it above the main pole in the vertical dimension rather than in the trailing gap space. This dimensional change allows the trailing gap to be narrowed for increased magnetic field strength while the oscillation device maintains its function in the vertical space above the pole structure.
4Speed
If the oscillation device is positioned in the trailing gap to generate high-frequency field, then high-frequency field generation is achieved, but the trailing gap thickness becomes non-uniform
Solution Approach 1:
The patent extracts the oscillation device from the trailing gap position and relocates it to a separate position above the main pole. This extraction removes the source of non-uniformity from the trailing gap region, allowing the trailing gap thickness to be controlled uniformly while the oscillation device continues to generate the required high-frequency magnetic field from its new position.
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 allows for increased recording densities while maintaining thermal stability and write-ability, as the magnetic capping layer helps in preserving the oscillation device's thickness and uniformity, thereby improving the performance of the MAMR head.
Implementation Method 1
an oscillation device positioned above the main pole in a track direction, the oscillation device being configured to generate a high-frequency magnetic field
Implementation Method 2
a magnetic capping layer positioned above the oscillation device in the track direction, the magnetic layer having a front region at a media facing side (MFS) of the magnetic recording head and a rear region positioned behind the front region in an element height direction, wherein a thickness of the front region of the magnetic capping layer is less than a thickness of the rear region thereof
Implementation Method 3
a main pole configured to generate a magnetic field for recording data on a magnetic recording medium
Data Source
AI summary
In one embodiment, a magnetic recording head includes: a main pole configured to generate a magnetic field for recording data on a magnetic recording medium; an oscillation device positioned above the main pole in a track direction, the oscillation device being configured to generate a high-frequency magnetic field; a magnetic capping layer positioned above the oscillation device in the track direction, the magnetic layer having a front region at a media facing side (MFS) of the magnetic recording head and a rear region positioned behind the front region in an element height direction, wherein a thickness of the front region of the magnetic capping layer is less than a thickness of the rear region thereof; and a trailing shield positioned above the magnetic capping layer in the track direction.