Magnetic Recording Head Spin Injection Layer Thickness Gradient
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Solution Overview
Problem
In high-frequency assisted magnetic recording heads, the non-uniform magnetic field in the write gap due to varying film thickness of the spin injection layer across the air bearing surface and deep position leads to unstable magnetization of the spin injection layer, making it difficult to achieve uniform magnetization rotation and efficient magnetization inversion in the recording layer.
Innovation Solution
The spin injection layer is made thicker in the deep position away from the air bearing surface than at the air bearing surface side, stabilizing the magnetization and ensuring uniform rotation of the oscillation layer, thereby enhancing magnetization inversion energy and recording density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the spin injection layer has constant film thickness from the air bearing surface side to the deep position, then the structure is simple and easy to manufacture, but the magnetization becomes unstable on the ABS side due to non-uniform magnetic field, making it difficult to achieve uniform magnetization rotation
Solution Approach 1:
The spin injection layer is designed with non-uniform film thickness where the thickness at the deep position (away from ABS) is greater than the thickness at the ABS side. This local variation in film thickness compensates for the non-uniform magnetic field distribution in the write gap, stabilizing the magnetization of the spin injection layer across different height positions and enabling uniform magnetization rotation.
2Reliability
If the spin injection layer is made thicker in the deep position than at the ABS side, then the magnetization stability is improved and uniform rotation is achieved, but the manufacturing precision requirement increases due to controlled thickness variation
Solution Approach 1:
The film thickness of the spin injection layer is varied as a function of position in the height direction, with the thickness at the deep position being greater than at the ABS side. This parameter change optimizes the magnetic field compensation effect, ensuring stable magnetization and reliable oscillation of the high-frequency assisted element while achieving uniform magnetization rotation across the write gap.
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 improves the recording resolution and overwrite performance by stabilizing the magnetization of the spin injection layer, leading to better oscillation and increased magnetization inversion energy in the recording medium.
Implementation Method 1
a spin-torque oscillator is provided in the write gap between the medium-side end portion of the write shield magnetic pole and the main magnetic pole. Current is supplied to the spin-torque oscillator through the main magnetic pole and the write shield magnetic pole.
Implementation Method 2
a high-frequency (microwave) assisted head wherein a microwave assisted element such as a spin-torque oscillator is provided in the write gap
Implementation Method 3
a main magnetic pole which produces a perpendicular magnetic field
Data Source
AI summary
According to one embodiment, a magnetic recording head includes an air bearing surface, a magnetic pole having a distal end portion, a write shield opposed to the distal end portion of the magnetic pole across a write gap, and a high-frequency oscillator between the magnetic pole and the write shield in the write gap. The high-frequency oscillator includes a spin injection layer, an intermediate layer and an oscillation layer which are stacked in a head travel direction. A film thickness of the spin injection layer in the head travel direction at a height position away from the air bearing surface is greater than a film thickness of the spin injection layer in the head travel direction on the air bearing surface.