Spin Torque Oscillator Magnetic Shielding for Recording Density
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Solution Overview
Problem
The challenge in achieving high-density magnetic recording is hindered by heat fluctuations and instability in the spin torque oscillator due to the strong write magnetic field generated from the main magnetic pole, which affects the oscillation frequency and current density, making it difficult to maintain reliable high-frequency magnetic field generation.
Innovation Solution
Incorporating a magnetic shield and sidewall magnetic layers adjacent to the spin torque oscillator to reduce the write magnetic field from the main magnetic pole, thereby stabilizing the oscillation characteristics and current density, and using a pin-flip spin torque oscillator to manage magnetic field polarity changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the spin torque oscillator is located close to the main magnetic pole to enable high-frequency field assist recording, then the recording density and capacity are improved, but the oscillation characteristics become unstable due to the strong write magnetic field
Solution Approach 1:
A nonmagnetic layer is introduced between the spin torque oscillator and the main magnetic pole to shield the oscillator from the strong write magnetic field. This intermediary layer allows the oscillator to be positioned close to the main magnetic pole for high-frequency field assist recording while preventing the write magnetic field from destabilizing the oscillation characteristics.
Solution Approach 2:
The magnetization direction of the spin injection layer is changed to be substantially perpendicular to the medium-facing surface, which alters the magnetic field distribution and reduces the impact of the write magnetic field on the oscillation characteristics while maintaining the high-frequency magnetic field generation capability.
2Productivity
If a strong write magnetic field is generated from the main magnetic pole for effective recording, then the recording efficiency is improved, but the oscillation frequency and current density of the spin torque oscillator vary greatly
Solution Approach 1:
The nonmagnetic layer serves as a magnetic field shield that allows the strong write magnetic field to effectively record data on the medium while preventing this field from penetrating to the spin torque oscillator and causing oscillation frequency variations.
Solution Approach 2:
The magnetic shield structure provides different magnetic field environments to different regions: the write magnetic field is allowed to act on the magnetic recording medium for efficient recording, while the spin torque oscillator region is shielded to maintain stable oscillation characteristics.
3Productivity
If the spin torque oscillator generates high-frequency magnetic field for high-density recording, then the coercive force reduction is improved, but the device complexity increases due to additional layers and structures
Solution Approach 1:
The spin injection layer serves multiple functions: it generates spin torque for high-frequency oscillation, provides magnetic field shielding when properly oriented, and can be integrated with the existing magnetic head structure. This multi-functionality reduces the need for separate shielding components.
Solution Approach 2:
The nonmagnetic layer that provides magnetic shielding is merged with the electrode layers that supply current to the spin torque oscillator, combining multiple functions into a single integrated structure and reducing overall device complexity.
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 reduces the variation in oscillation characteristics and current density, allowing for more stable high-frequency magnetic field generation with reduced heat generation, enhancing recording efficiency and density on magnetic media with high magnetic anisotropic energy.
Implementation Method 1
the magnetization of the oscillation layer ferromagnetically resonates by virtue of the spin torque generated from the spin injection layer
Implementation Method 2
the magnetization of the oscillation layer ferromagnetically resonates by virtue of the spin torque generated from the spin injection layer. As a result, a high-frequency magnetic field is generated from the spin torque oscillator
Implementation Method 3
a magnetic shield that is provided to face surfaces of the recording magnetic pole and the second magnetic layer, the surfaces existing in a track movement direction, a distance between the magnetic shield and the second magnetic layer being shorter than a distance between the recording magnetic pole and the magnetic shield
Data Source
AI summary
It is made possible to reduce the write magnetic field generated from the main magnetic pole toward the spin torque oscillator, so as to reduce the variation in the oscillation characteristics of the spin torque oscillator, and reduce the current required for oscillation. The magnetic head assembly includes: a recording magnetic pole; a spin torque oscillator that has first and second magnetic layers, and an intermediate layer interposed between the first and second magnetic layers, the spin torque oscillator generating a high-frequency magnetic field by applying a current between the first and second magnetic layers; and a third magnetic layer that is placed adjacent to at least part of a side face of the second magnetic layer.