Magnetic Recording Medium With Gradient Anisotropy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic recording media face a challenge in achieving both high thermal stability and favorable writing capability as the reduction in magnetic crystal grain size for increased recording density leads to decreased thermal stability and increased magnetic switching fields, affecting writing capability.
Innovation Solution
A process involving the formation of a magnetic recording medium with a first and second magnetic recording layer, where the substrate temperature is monotonously changed during deposition, using a binary ordered alloy for the first layer and a ternary-or-higher ordered alloy for the second layer, with different materials and non-magnetic grain boundaries to control magnetic anisotropy constants and maintain thermal stability while enhancing writing capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the grain diameter of magnetic crystal grains is reduced to increase recording density, then recording density is improved, but thermal stability of recorded magnetization deteriorates
Solution Approach 1:
The patent applies local quality by creating a magnetic recording layer with spatially varying composition and structure. The layer contains a first region with higher magnetic anisotropy constant (higher Ku) and a second region with lower magnetic anisotropy constant (lower Ku), where the boundary between regions is blurred rather than sharp. This local variation allows different regions to serve different functions: the high-Ku region provides thermal stability while the low-Ku region facilitates writing, resolving the contradiction between recording density and thermal stability.
2Productivity
If the grain diameter of magnetic crystal grains is reduced to increase recording density, then recording density is improved, but magnetic switching field increases, deteriorating writing capability
Solution Approach 1:
The patent resolves the writing capability contradiction through local quality by introducing a magnetic recording layer with a gradient in magnetic anisotropy constant. The first region with higher Ku is positioned to maintain thermal stability, while the second region with lower Ku is positioned to reduce the magnetic switching field, thereby improving writing capability. The blurred boundary between regions ensures smooth transition and prevents abrupt changes that would cause writing difficulties.
3Reliability
If L10 type ordered alloys are used to increase magnetocrystalline anisotropy for thermal stability, then thermal stability is improved, but the degree of order decreases due to substrate temperature drop, requiring repeated heating and deposition steps
Solution Approach 1:
The patent applies parameter changes by controlling the substrate temperature during the deposition of the magnetic recording layer. By maintaining the substrate temperature above a specific threshold (e.g., 100°C or higher), the patent prevents the decrease in degree of order that would otherwise occur. This temperature control allows the formation of L10 type ordered alloys with high magnetocrystalline anisotropy in a single deposition process, eliminating the need for repeated heating and deposition steps, thus reducing production process complexity while maintaining thermal stability.
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 allows for the production of a magnetic recording medium with excellent thermal stability and writing capability, as evidenced by reduced coercive force and improved recording density without compromising signal integrity.
Implementation Method 1
the magnetic crystal grains in the magnetic layer need to be formed of materials with higher magnetocrystalline anisotropies, in order to compensate the decrease in thermal stability
Implementation Method 2
a method for producing a perpendicular magnetic recording medium having a magnetic recording layer of a desired thickness, by repeating the steps of heating a substrate and depositing a film of the L10 type ordered alloy
Data Source
AI summary
The problem of the invention is to provide a process for producing a magnetic recording medium which exhibits both of excellent thermal stability and favorable writing capability. The process for producing the magnetic recording medium of the invention includes the steps of: (A) forming the first magnetic recording layer while monotonously changing a substrate temperature; and (B) forming the second magnetic recording layer while monotonously changing the substrate temperature wherein the material of the second magnetic recording layer is different from the material of the first recording layer, wherein the substrate temperature at the beginning of the step (B) is set such that the magnetic anisotropy constant of the first magnetic recording layer and the magnetic anisotropy constant of the second magnetic recording layer is changed monotonously at the interface between the first and second magnetic recording layers.