Cryogenic Magnetic Write Pole Grain Control
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Solution Overview
Problem
In data storage devices, residual magnetic flux after data programming can lead to unintended erasure of data bits due to unpowered magnetic writers emitting flux, and high temperature annealing causes abnormal grain growth in magnetic layers, deteriorating their soft magnetic properties, necessitating improved magnetic writing elements with controlled erase after write (EAW) and thermal stability.
Innovation Solution
A magnetic writing element with a write pole tuned to a predetermined grain size using a cryogenic substrate temperature, combined with a magnetic shield of matching grain size, inhibits surface and bulk diffusion during deposition, maintaining small nano-crystalline grains and enhancing thermal stability and soft magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high temperature annealing is applied to magnetic layers, then grain growth occurs, but soft magnetic properties deteriorate
Solution Approach 1:
The patent applies cryogenic substrate temperature (e.g., 50K) during deposition to control grain size parameters, preventing the abnormal grain growth that occurs with high temperature annealing while maintaining soft magnetic properties. This parameter change in deposition temperature compensates for the harmful effects of subsequent thermal processing.
Solution Approach 2:
The patent performs preliminary grain size control during deposition at cryogenic temperatures before annealing occurs. By establishing small, stable grain structures in advance, the magnetic layers are pre-protected against the harmful grain growth and property deterioration that would otherwise result from high temperature annealing.
2Reliability
If unpowered magnetic writers are present, then residual magnetic flux is emitted, but data bits are inadvertently erased
Solution Approach 1:
The patent modifies the magnetic properties of the write pole by controlling grain size through cryogenic deposition, achieving low easy axis coercivity and high magnetization relaxation. These parameter changes enable the write pole to rapidly release residual magnetic flux, preventing EAW while maintaining necessary write capability when powered.
Solution Approach 2:
The patent designs the write pole with optimized magnetic properties that allow it to function temporarily during writing operations and then rapidly relax to a neutral state. The write pole effectively serves its purpose during powered operation and then 'resets' quickly by releasing residual flux, preventing harmful effects during unpowered periods.
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 easy axis coercivity, improves magnetization relaxation, and increases thermal stability, leading to enhanced data recording accuracy and reliability in high-density data storage devices by preventing abnormal grain growth and improving magnetic properties.
Implementation Method 1
inhibits surface and bulk diffusion during deposition, maintaining small nano-crystalline grains
Implementation Method 2
tuned to a predetermined first grain size with a cryogenic substrate temperature
Data Source
AI summary
An apparatus and associated method provides a magnetic writing element that may have at least a write pole tuned to a predetermined first grain size with a cryogenic substrate temperature. A magnetic shield can be formed with a predetermined second grain size that is tuned with the cryogenic substrate temperature.