Spin Torque Oscillator High Damping Layer MAMR Write Heads
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Solution Overview
Problem
Current microwave assisted magnetic recording (MAMR) write heads face challenges in achieving high recording densities due to the limitations of small main pole dimensions, which result in reduced recording fields and difficulty in detecting oscillations of the spin torque oscillator (STO) device, especially with larger field generation layer volumes.
Innovation Solution
Incorporating a high damping field generation layer or a damping enhancing capping layer in the STO device, utilizing magnetic alloys and rare earth or heavy metals, to achieve damping in the range of 0.5% to 20%, enhancing the amplitude and coherence of oscillations and maintaining a high magnetic moment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the main pole size is reduced to achieve higher recording density, then recording density is improved, but the recording field strength decreases
Solution Approach 1:
A spin torque oscillator device is introduced as an intermediary between the write element and the magnetic recording medium. This STO device includes a spin polarization layer and a field generation layer that converts electrical current into high-frequency magnetic fields through spin transfer torque, providing an additional field component that assists the main pole in achieving high recording density without requiring the main pole to be excessively small
Solution Approach 2:
The field generation layer uses materials with specific damping parameters (alpha ≥ 0.1) to control the oscillation characteristics. By adjusting the damping parameter and layer thickness, the system optimizes the microwave field generation efficiency, enabling effective assistance to the main pole field while maintaining stable oscillation
2Power
If the field generation layer volume is increased to improve microwave field strength, then microwave field strength is improved, but oscillation detection becomes more difficult
Solution Approach 1:
The field generation layer is designed with specific damping parameters (alpha ≥ 0.1) and thickness (5-20 nm) to optimize the balance between microwave field strength and oscillation detectability. These parameter adjustments ensure that the layer generates sufficient microwave power while maintaining coherent oscillation that can be detected through magnetoresistive effects in adjacent layers
Solution Approach 2:
The STO device employs a composite structure combining a spin polarization layer (e.g., CoFeB, CoFe) with a high-damping field generation layer (e.g., CoFe alloy with specific composition). This composite structure enables the spin polarization layer to generate spin torque while the field generation layer produces strong microwave fields with detectable oscillation characteristics
3Stability of the object's composition
If damping is increased to enhance oscillation coherence and amplitude, then oscillation coherence is improved, but energy loss increases
Solution Approach 1:
The damping parameter of the field generation layer is optimized to a specific range (alpha ≥ 0.1, typically 0.1-0.5) that provides sufficient oscillation coherence and amplitude enhancement while minimizing excessive energy dissipation. This parameter optimization ensures that the microwave field generation is efficient and sustainable
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 high damping layer enables coherent oscillation and increased amplitude of magnetization, facilitating the detection of microwave fields and improving recording density by stabilizing magnetization and reducing coercive forces, thus enhancing the performance of MAMR write heads.
Implementation Method 1
a spin polarization layer, a spacer layer over the spin polarization layer, and a field generation layer over the spacer layer
Implementation Method 2
The field generation layer has a damping in a range from about 0.5% to about 20%
Data Source
AI summary
Embodiments of the present disclosure generally relate to a spin torque oscillator device (STO) including a high damping field generation layer or a damping enhancing capping layer for use in microwave assisted magnetic recording (MAMR) write heads. In one embodiment, a STO device for a MAMR write head includes a spin polarization layer, a spacer layer over the spin polarization layer, and a field generation layer over the spacer layer. The field generation layer has a damping in a range from about 0.5% to about 20%.