Spin Orbital Torque Recording Head Layer Segmentation
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Solution Overview
Problem
Energy-assisted write heads based on spin-orbital torque (SOT) face challenges in achieving effective magnetization switching due to the difficulty in controlling the thickness of the spin-torque layer (STL), leading to low or non-existent assisting DC field generation.
Innovation Solution
Incorporating a first and second spin torque layer between the spin Hall layer and the trailing shield and main pole, respectively, with charge current blocking layers to enhance spin injection efficiency and maintain the correct thickness for effective magnetization switching, thereby generating a stronger assisting DC field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the spin-torque layer thickness is increased to remain after planarization, then manufacturing reliability is improved, but spin orbital torque effectiveness deteriorates due to SOT being a surface phenomenon
Solution Approach 1:
The patent divides the single spin-torque layer into two separate spin-torque layers positioned on opposite sides of the spin Hall layer. This segmentation allows each layer to be independently optimized for thickness to maintain effectiveness after planarization while ensuring at least one layer remains sufficiently thin to respond to spin orbital torque from the spin Hall layer.
Solution Approach 2:
The patent transitions from a single-layer configuration to a multi-layer configuration by adding the spin-torque layers on both sides of the spin Hall layer. This dimensional change in layer arrangement provides additional degrees of freedom for thickness optimization, allowing the structure to maintain SOT effectiveness while surviving planarization processes.
2Manufacturing precision
If the spin-torque layer thickness is decreased to maintain SOT effectiveness, then spin orbital torque effectiveness is improved, but manufacturing reliability deteriorates as the layer may be removed during planarization
Solution Approach 1:
By segmenting the spin-torque functionality into two separate layers on opposite sides of the spin Hall layer, the patent ensures that even if one thin layer is removed during planarization, the other layer remains to provide the necessary spin orbital torque effectiveness.
Solution Approach 2:
The patent provides a backup spin-torque layer configuration where having layers on both sides of the spin Hall layer creates a cushioning effect against planarization variability. This redundant arrangement ensures that manufacturing variations in planarization depth do not eliminate the SOT functionality.
3Manufacturing precision
If a single thick spin-torque layer is used to survive planarization, then manufacturing precision is improved, but spin injection efficiency deteriorates due to reduced spin orbital coupling
Solution Approach 1:
The patent segments the spin-torque functionality into two thin layers rather than one thick layer, allowing each layer to maintain strong spin orbital coupling with the spin Hall layer while collectively providing sufficient robustness to survive planarization processes.
Solution Approach 2:
The patent creates a composite multi-layer structure consisting of the spin Hall layer sandwiched between two spin-torque layers. This composite configuration combines the advantages of thin layers (high spin injection efficiency) with the advantages of a multi-layer structure (improved manufacturing robustness).
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 increases the effective spin injection efficiency, reduces critical switching current density, and improves energy efficiency and reliability by ensuring the SOT structure remains effective during planarization, resulting in a higher areal density for magnetic recording.
Implementation Method 1
charge current through a spin Hall layer generates a spin current in the spin Hall layer. The spin orbital coupling of the spin Hall layer and a spin torque layer (STL) causes switching or precession of magnetization of the STL by the spin orbital coupling of the spin current from the spin Hall layer
Implementation Method 2
The spin orbital coupling of the spin Hall layer and a spin torque layer (STL) causes switching or precession of magnetization of the STL by the spin orbital coupling of the spin current from the spin Hall layer
Implementation Method 3
Switching or precession of the magnetization of the field generation layer generates an assisting field to the write field
Implementation Method 4
Switching or precession of the magnetization of the STL can generate an assisting DC field or AC field to the write field
Data Source
AI summary
A magnetic recording head includes a trailing shield, a main pole, and a spin Hall layer. The spin Hall layer is disposed between the trailing shield and the main pole. A first spin torque layer is disposed between the spin Hall layer and the trailing shield. A second spin torque layer is disposed between the spin Hall layer and the main pole.