Dual-Spin Torque Oscillator Write Heads for High-Density Recording
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As the size of writers in hard disk drives decreases to accommodate increasing digital data storage demands, writability degrades, necessitating improved techniques for writing to magnetic recording media.
Innovation Solution
Implementing a perpendicular magnetic recording writer with dual spin torque oscillators (STOs) that oscillate in the same frequency but out of phase, utilizing mutual spin transfer torques to generate a magnetic field that assists in writing to the magnetic recording medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the size of writers is decreased to accommodate increasing digital data storage demands, then areal density capability is improved, but writability degrades
Solution Approach 1:
The write head is segmented into multiple functional components: a main pole for generating the primary magnetic field, multiple spin torque oscillators (STOs) for generating microwave fields, and a trailing shield for magnetic flux containment. This segmentation allows each component to be optimized independently for its specific function while working together to solve the writability problem in high-density configurations.
Solution Approach 2:
The spin torque oscillators generate microwave fields through periodic oscillation of magnetic moments at high frequencies (typically 10-100 GHz). This periodic action creates time-varying magnetic fields that resonantly couple with the magnetic bits, providing thermal assistance for writing without requiring increased current density or writer size.
2Reliability
If multiple spin torque oscillators are used to generate microwave fields, then write performance is improved, but device complexity increases
Solution Approach 1:
Multiple spin torque oscillators are merged into a single integrated write head assembly, with the STOs positioned adjacent to each other and magnetically coupled through shared magnetic paths. This merging allows the individual STO devices to function as a unified system that generates enhanced microwave fields while occupying minimal space within the write head structure.
Solution Approach 2:
The spin torque oscillators serve multiple functions simultaneously: they generate microwave fields for writing assistance, act as magnetic flux guides through their oscillating moments, and provide thermal management through their resistive heating. This multi-functionality reduces the need for separate dedicated components, thereby managing device complexity while improving write performance.
3Manufacturing precision
If spin torque oscillators oscillate out of phase to maximize rf field component along written track, then write accuracy is improved, but control difficulty increases
Solution Approach 1:
The oscillation phase relationship between multiple STOs is controlled through feedback mechanisms that monitor the microwave field generation and adjust the drive currents to each STO accordingly. This feedback ensures that the STOs oscillate out of phase by the optimal amount to maximize the rf field component along the written track direction while minimizing perpendicular components, achieving write accuracy without excessive control complexity.
Solution Approach 2:
The phase relationship between STOs is controlled by adjusting electrical parameters such as drive current magnitude and frequency, as well as magnetic parameters including the magnetic moment orientation and coupling strength between STOs. By optimizing these parameters, the system achieves the desired out-of-phase oscillation that maximizes write accuracy along the track direction.
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
Enhances write performance by maximizing the component of the rf field along the written track direction while minimizing detrimental components perpendicular to the medium, improving writer robustness and areal density capability.
Implementation Method 1
Mutual spin transfer torques can be configured to be enabled between adjacent layers in the spin torque device. The FGL layers for each of the at least two STOs can be configured to be driven into an angle oscillation as a result of the mutual spin transfer torques
Implementation Method 2
The oscillation between the FGLs can cause a magnetic field to be generated that can assist in writing to a magnetic recording medium
Data Source
AI summary
The present embodiments relate to write heads implementing microwave-assisted magnetic recording utilizing multiple spin torque oscillators (STOs). Each STO can include a field-generation layer (FGL) that can oscillate in a same frequency and out of phase with one another. The layers in each STO can enable mutual spin transfer torques between adjacent layers, which can drive the FGLs into a large angle oscillation. The oscillation between the FGLs can cause a magnetic field to be generated that can assist in writing to a magnetic recording medium.