Spin Torque Oscillator Corner Angle for Microwave Assisted Recording
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Solution Overview
Problem
In magnetic recording, smaller magnetic grains lead to reduced thermal stability, and increasing magnetic anisotropy energy results in an excessive anisotropic magnetic field, exceeding the recording magnetic field intensity limit, causing recording failures in microwave assisted magnetic recording systems.
Innovation Solution
A microwave assisted magnetic head design with a spin torque oscillator that has a specific end surface angle configuration, where the first angle θ1 is smaller than the second angle θ2, ranging from 80 to 100 degrees, allowing for stable oscillation and sufficient assist effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the magnetic anisotropy energy Ku of the magnetic grains is increased to improve thermal stability, then the thermal stability of magnetic grains is improved, but the anisotropic magnetic field becomes excessive and exceeds the recording magnetic field intensity limit
Solution Approach 1:
A spin torque oscillator is introduced as an intermediary component between the main magnetic pole and trailing shield. This oscillator generates a microwave magnetic field that acts as a mediator to assist the recording process, enabling the system to overcome the excessive anisotropic magnetic field barrier while maintaining high thermal stability through high Ku magnetic materials.
Solution Approach 2:
The patent changes the operational parameters by introducing microwave frequency magnetic field oscillation. The spin torque oscillator operates at microwave frequencies to induce magnetization precession in the recording layer, transforming the recording mechanism from direct magnetic field application to oscillation-assisted switching, thereby enabling recording on high Ku media.
2Power
If the main magnetic pole and spin torque oscillator are placed close to each other to provide sufficient assist effect, then the assist effect is enhanced, but the spin torque oscillator oscillates unevenly and the oscillation frequency fluctuates widely
Solution Approach 1:
The patent applies local quality by creating a non-uniform magnetic field distribution through the specific geometric configuration of the spin torque oscillator. The tapered structure with different angles (θ1 < θ2, where θ2 is 80-100 degrees) at different regions of the oscillator generates localized field variations that stabilize the oscillation while maintaining strong interaction with the recording layer.
Solution Approach 2:
The spin torque oscillator is designed with an asymmetric tapered structure where the first angle θ1 formed by the first end face and second end face is smaller than the second angle θ2 formed by the second end face and third end face. This asymmetric geometry creates a specific magnetic field distribution pattern that stabilizes the oscillation frequency while maintaining sufficient assist effect.
3Productivity
If smaller magnetic grains are used to increase recording density, then the recording density is increased, but the magnetic grains become less thermally stable due to reduced volume
Solution Approach 1:
The patent fundamentally changes the recording mechanism by introducing microwave-assisted magnetic recording. This parameter change enables the use of high Ku magnetic materials with small grain sizes, as the oscillation-assisted switching mechanism overcomes the high anisotropic energy barrier that would otherwise prevent recording on such media.
Solution Approach 2:
The spin torque oscillator acts as a mediator that provides the additional energy needed to switch magnetization in small, high Ku magnetic grains. The microwave magnetic field generated by the oscillator assists the main magnetic pole in overcoming the high anisotropic barrier, enabling stable recording on densely packed small grains.
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
The design ensures the spin torque oscillator oscillates evenly at a stable frequency, generating a sufficient microwave magnetic field intensity for effective recording on high magnetic anisotropy energy media, overcoming thermal stability and field intensity limitations.
Implementation Method 1
a microwave magnetic field of a frequency corresponding to the effective magnetic field (Heff) for magnetization of the recording layer of a magnetic recording medium is applied in the medium in-plane direction, whereby magnetization precession is excited in the recording layer
Implementation Method 2
With a current applied along the lamination direction of the spin torque oscillator 10′, the spin torque oscillator 10′ generates a microwave magnetic field through its own oscillation
Implementation Method 3
a main magnetic pole 6′ generating a recording magnetic field to apply to a magnetic recording medium 100′
Implementation Method 4
With the microwave magnetic field and recording magnetic field applied to the magnetic recording medium 100′ in a superimposed manner, magnetization precession is induced in the recording layer, and the perpendicular magnetization of the recording layer is inverted
Data Source
AI summary
A microwave assisted magnetic head includes a main magnetic pole; a trailing shield; and a spin torque oscillator provided between the main magnetic pole and the trailing shield. The spin torque oscillator has a first end surface configuring a part of an air bearing surface, a second end surface facing the main magnetic pole, and a third end surface facing the first end surface, the first angle θ1 made by the first end surface and the second end surface is smaller than the second angle θ2 formed by the second end surface and the third end surface, and the second angle θ2 is 80 to 100 degrees.