Magnetic Recording Head Nonmagnetic Layer Spin Wave Control
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Solution Overview
Problem
High-frequency-assisted magnetic recording heads face challenges in maintaining effective magnetization rotation and recording density due to spin wave disturbances, leading to reduced magnetic field gradient and recording resolution.
Innovation Solution
Incorporating a magnetic layer of high-magnetic-permeability material and a nonmagnetic layer with dispersed magnetic microparticles outside the high-frequency oscillator, which restricts spin wave transmission and enhances the oscillation magnetic field, thereby improving recording performance and density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the spin injection layer and oscillation layer are allocated in the write gap to create a high-frequency oscillator, then high-frequency assisted recording is achieved, but spin wave disturbance occurs that inhibits the assist effect
Solution Approach 1:
A nonmagnetic layer is introduced as an intermediary between the oscillation layer and the write shield magnetic pole/main magnetic pole. This nonmagnetic layer acts as a barrier that blocks spin wave transmission from the oscillation layer to the magnetic poles, preventing spin wave disturbance while allowing the high-frequency oscillation field to effectively assist magnetization reversal in the recording layer.
2Extent of automation
If current is supplied through the main magnetic pole and write shield magnetic pole to the spin-torque oscillator, then the high-frequency oscillator operates, but spin waves are generated that disturb magnetization rotation
Solution Approach 1:
The spin waves generated by the spin-torque oscillator are blocked by the nonmagnetic layer, converting the potentially harmful spin wave propagation into a contained phenomenon. The spin waves remain localized near the oscillation layer where they can be dissipated harmlessly, while the beneficial high-frequency oscillation field continues to assist magnetic recording without causing saturation or disturbance to the magnetic poles.
3Manufacturing precision
If the magnetic field gradient is increased to improve recording resolution, then recording density improves, but spin wave disturbance reduces the magnetic field gradient
Solution Approach 1:
The nonmagnetic layer serves as a protective intermediary that shields the magnetic poles from spin wave interference. By blocking spin wave transmission, it preserves the magnetic field gradient that is essential for high recording resolution, allowing the system to achieve improved areal density without the degrading effects of spin wave-induced field distortion.
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 stabilizes magnetization rotation, increases magnetic field strength and gradient, and enhances recording density by preventing spin wave disturbance and recording saturation, resulting in improved areal density in hard disk drives.
Implementation Method 1
a high-frequency (microwave) oscillator such as a spin-torque oscillator is provided in the write gap between the write shield magnetic pole and the main magnetic pole
Implementation Method 2
a magnetic layer formed of a high-magnetic-permeability material
Implementation Method 3
a nonmagnetic layer in which magnetic microparticles are dispersed, the nonmagnetic layer being provided outside the magnetic layer
Data Source
AI summary
According to one embodiment, a magnetic recording head includes an air bearing surface, a magnetic core including a main magnetic pole and a write shield arranged to face the main magnetic pole with a write gap, a coil, and a high-frequency oscillator provided between the main magnetic pole and the write shield in the write gap. The magnetic core includes an opposite surface facing a film surface of the high-frequency oscillator, a magnetic layer, and a nonmagnetic layer in which magnetic microparticles are dispersed. The nonmagnetic layer is provided outside the magnetic layer in at least a part of the opposite surface of the magnetic core.