Perpendicular Magnetic Recording Layer with Gradient Anisotropy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current perpendicular magnetic recording media face challenges in achieving high recording density due to thermal instability caused by small grain sizes, which limits the magnetic anisotropy constant, leading to low writability and increased transition noise when trying to maintain thermal stability and high anisotropic energy.
Innovation Solution
A recording layer with a concentration of implanted ions is used to create regions with varying magnetic anisotropy constants, achieved through ion irradiation, allowing for a continuous gradient of magnetic anisotropy, improving thermal stability and writability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the grain size is reduced to increase recording density, then the recording density increases, but the thermal stability decreases due to superparamagnetic effect
Solution Approach 1:
The patent changes the magnetic anisotropy constant parameter by introducing heavy metal elements (Pt, Pd, Ir, etc.) into the magnetic layer or forming composite structures with high anisotropy materials. This parameter change allows maintaining thermal stability at higher recording densities by increasing the energy barrier against thermal fluctuations, thereby resolving the contradiction between increased recording density and maintained thermal stability.
Solution Approach 2:
The patent employs composite material structures such as CoCrPt, CoCrPd, CoFeB with heavy metal additions, or multilayer structures combining magnetic layers with high anisotropy materials. These composite materials provide both the fine grain structure needed for high density and the enhanced magnetic anisotropy required for thermal stability, thus resolving the contradiction between recording density and thermal stability.
2Reliability
If the magnetic anisotropy constant is increased to maintain thermal stability, then the thermal stability improves, but the coercivity increases making magnetization reversal difficult
Solution Approach 1:
The patent applies local quality by creating spatial variations in magnetic anisotropy constant and coercivity within the recording layer. Different regions or grain structures are engineered with locally optimized properties, allowing some areas to have high anisotropy for thermal stability while other areas maintain lower coercivity for easier writing, thus resolving the contradiction between thermal stability and writability.
Solution Approach 2:
The patent introduces dynamic control mechanisms such as using magnetic field gradients, pulsed field application, or time-dependent anisotropy modulation during the writing process. This dynamic approach allows temporary reduction of effective coercivity during writing while maintaining high static anisotropy for thermal stability, resolving the contradiction between thermal stability and writability.
3Ease of operation
If different magnetic layers with different anisotropy constants are formed to solve writability issues, then the writability improves, but the material selection is limited and manufacturing becomes difficult
Solution Approach 1:
The patent segments the magnetic recording layer into multiple functional regions or sub-layers, each with optimized magnetic properties. This segmentation allows independent optimization of writing and reading characteristics while using a unified manufacturing process, reducing material selection constraints and simplifying manufacturing compared to forming entirely separate magnetic layers with different anisotropy constants.
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 solution enhances thermal stability and writability by maintaining high magnetic anisotropy while reducing coercivity, enabling higher recording densities with improved signal-to-noise ratios and stable data storage.
Implementation Method 1
A magnetic field generated from a recording head (not shown) passes through the soft-magnetic underlayer 12 and returns to the recording head, thereby forming a magnetic path H. At this time, a perpendicular component of the magnetic field magnetizes magnetic domains of the recording layer 16 and records information.
Implementation Method 2
the required magnetic anisotropy constant KU is 1.997E7 erg/cc. However, it is difficult for a current recording head to record data in a magnetic recording medium having a large magnetic anisotropy constant KU.
Data Source
AI summary
An apparatus having a recording layer of a magnetic material with a concentration of implanted ions that increases in relation to a thickness direction of the recording layer to provide the recording layer with a continuously varied perpendicular magnetic anisotropy constant.