Magnetic Recording Medium W Underlayer SN Ratio
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge is to further reduce the size of magnetic crystal particles in magnetic recording media while maintaining thermal stability and high magnetic anisotropy, and to minimize exchange coupling between these particles to achieve a high signal-to-noise (SN) ratio, without degrading the magnetic anisotropy constant Ku.
Innovation Solution
A magnetic recording medium is developed with a substrate and multiple underlayers, including a crystalline underlayer containing tungsten (W) with 1-20 mol% of elements like B, Si, or C, and a barrier layer with a NaCl structure, which helps in achieving uniform particle diameters and reducing variance in coercivity, thereby enhancing the SN ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a large amount of grain boundary phase material (SiO2 or C) is added to reduce magnetic particle diameter and minimize exchange coupling between particles, then the SN ratio is improved, but the magnetic anisotropy constant Ku is reduced due to degradation of the degree of order of magnetic layer crystal particles
Solution Approach 1:
An underlayer containing W and 1-20 mol% of B, Si, or C is introduced as an intermediary between the substrate and the magnetic layer. This underlayer mediates the contradiction by controlling the crystal particle diameter and orientation of the magnetic layer, enabling the use of smaller magnetic particles with reduced exchange coupling (improving SN ratio) while maintaining the magnetic anisotropy constant Ku through proper crystal orientation control.
2Quantity of substance
If the magnetic particle diameter is reduced to increase storage capacity, then the area density is improved, but the thermal stability and magnetic anisotropy are degraded
Solution Approach 1:
The underlayer composition is optimized by controlling the content of W and 1-20 mol% of B, Si, or C to achieve the desired crystal particle diameter and orientation. This parameter control enables the magnetic layer to maintain high magnetic anisotropy and thermal stability even with reduced particle diameter, thereby increasing area density without sacrificing thermal stability.
3Manufacturing precision
If the crystal particle diameter of the magnetic layer is reduced to minimize exchange coupling between particles, then the SN ratio is improved, but the variance in coercivity increases
Solution Approach 1:
The underlayer provides localized control over the crystal particle formation in the magnetic layer by incorporating 1-20 mol% of B, Si, or C. This local compositional control ensures uniform crystal particle diameter and orientation, reducing variance in coercivity while maintaining small particle size for high SN ratio.
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 maintains the degree of order of the magnetic layer's crystal particles, reduces variance in particle diameters, and improves the SN ratio, facilitating better separation and reduced exchange coupling of crystal particles, thus enhancing the performance of magnetic storage apparatuses.
Implementation Method 1
At least one of the multiple underlayers is a crystalline underlayer containing W. The crystalline underlayer further contains 1 mol % or more to 20 mol % or less of one or more kinds of elements selected from B, Si, and C.
Implementation Method 2
A barrier layer including a material having a NaCl structure is formed between the crystalline underlayer and the magnetic layer.
Implementation Method 3
The main component of the magnetic layer is an alloy having an L10 structure. size reduction of magnetic particles of the magnetic recording medium can be achieved while maintaining thermal stability
Data Source
AI summary
A magnetic recording medium includes a substrate, multiple underlayers formed on the substrate, and a magnetic layer formed on the multiple underlayers. A main component of the magnetic layer is an alloy having a L10 structure. At least one of the multiple underlayers is a crystalline underlayer containing W. The W is a main component of the crystalline underlayer. The crystalline underlayer further contains 1 mol % or more to 20 mol % or less of one or more kinds of elements selected from B, Si, and C. A barrier layer including a material having a NaCl structure is formed between the crystalline underlayer and the magnetic layer.