Magnetic Recording Medium Sidewall Pattern Anisotropy
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Solution Overview
Problem
Conventional magnetic recording media face challenges in achieving higher density due to thermal stability issues with fine magnetic grains, requiring more intense magnetic fields and precise timing for data writing, which is difficult to achieve with existing technologies.
Innovation Solution
A magnetic recording medium is developed with recording cells comprising a ferromagnetic pattern and a magnetic pattern on one sidewall, where the magnetic pattern has a lower crystalline magnetic anisotropy constant than the ferromagnetic pattern, allowing for easier magnetization reversal with a lower recording magnetic field and broader timing margin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If magnetic grains are made finer to form smaller recording marks, then recording density is improved, but thermal stability deteriorates causing thermal fluctuation problems
Solution Approach 1:
The invention divides the magnetic recording layer into isolated magnetic grains separated by nonmagnetic regions. This segmentation prevents magnetic interaction between adjacent grains while maintaining fine grain sizes for high density, thereby solving the thermal fluctuation problem that occurs when grains are made finer without segmentation.
Solution Approach 2:
The invention creates local heterogeneity by introducing nonmagnetic regions between magnetic grains. This local quality change allows different regions to have distinct functions: magnetic grains for data storage and nonmagnetic regions for isolation, enabling fine grains to maintain thermal stability through reduced magnetic interaction.
2Reliability
If thermal stability of magnetic material is improved to solve thermal fluctuation problem, then thermal stability is improved, but resistance to recording magnetic field increases requiring more intense magnetic field
Solution Approach 1:
By segmenting the magnetic layer into isolated grains, the invention reduces the total magnetic moment that needs to be reversed during recording. Each grain can be switched independently with lower field strength, offsetting the increased anisotropy energy from improved thermal stability materials.
Solution Approach 2:
The invention changes the magnetic structure from continuous to discontinuous (segmented grains), which alters the magnetic switching characteristics. This parameter change allows the use of materials with higher anisotropy for thermal stability while maintaining recordability through reduced demagnetizing fields in the segmented structure.
3Reliability
If recording cells are formed by lithography to increase grain size, then thermal fluctuation problem is solved, but writing precision becomes more difficult due to synchronization requirements
Solution Approach 1:
The invention uses a perpendicular magnetic recording system where the write head generates a time-varying magnetic field that dynamically switches magnetization in recording cells. This dynamic approach provides a timing window for successful writing, reducing the precision requirements compared to static synchronous writing schemes.
Solution Approach 2:
The invention transitions from in-plane magnetization to perpendicular magnetization. This dimensional change in magnetization orientation provides better magnetic isolation between adjacent cells and extends the timing window for successful writing, thereby reducing write timing precision requirements.
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 solution enables higher density magnetic recording with reduced thermal fluctuations and improved precision in data writing, allowing for more efficient data storage with lower magnetic field requirements.
Implementation Method 1
a magnetic pattern formed on one sidewall of the ferromagnetic pattern in the track direction and having a lower crystalline magnetic anisotropy constant Ku than that of the ferromagnetic pattern
Implementation Method 2
a magnetic pattern formed on one sidewall of the ferromagnetic pattern in the track direction
Data Source
AI summary
A magnetic recording medium includes a disk substrate, and recording cells arrayed on the disk substrate in a track direction, the recording cells includes a ferromagnetic pattern and a magnetic pattern formed on one of two sidewalls of the ferromagnetic pattern in the track direction and having a lower crystalline magnetic anisotropy constant Ku than that of the ferromagnetic pattern.