Magnetic Recording Medium Barrier Layer Grain Ordering
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Solution Overview
Problem
Existing magnetic recording technologies face challenges in reducing magnetic crystal grain size and exchange coupling while maintaining thermal stability and crystal anisotropy, particularly when using high-Ku materials like L10 type alloys, which deteriorates the ordering of crystal grains and affects signal-to-noise ratio (SNR) in magnetic storage apparatuses.
Innovation Solution
A magnetic recording medium is designed with a substrate, a magnetic layer having an L10 type crystal structure, multiple underlayers including Mo with Si and C, and a barrier layer of NaCl structure, which helps in reducing coercivity distribution and promoting uniform crystal grain growth, thereby improving SNR without deteriorating the ordering of crystal grains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If grain boundary material is added to reduce magnetic grain size, then medium SNR is improved, but ordering of L10 type alloy crystal grains deteriorates
Solution Approach 1:
The patent introduces a barrier layer made of NaCl-structured material (such as MgO) positioned between the magnetic layer containing grain boundary material and the underlayer. This barrier layer segments the structure to prevent the grain boundary material from diffusing into the underlayer and disrupting the L10 type alloy ordering, while still allowing the grain boundary material to function in isolating magnetic grains within the magnetic layer itself.
Solution Approach 2:
The NaCl-structured barrier layer acts as an intermediary between the magnetic layer and the underlayer. It mediates the interaction by providing a physical barrier that prevents harmful diffusion of grain boundary material into the underlayer, thereby protecting the ordering of L10 type alloy crystal grains while allowing the magnetic layer to maintain its desired granular structure for high SNR.
2Quantity of substance
If magnetic grain size is reduced to increase recording density, then thermal stability is maintained, but exchange coupling between grains increases
Solution Approach 1:
The patent applies local quality by adding grain boundary material specifically at the boundaries between magnetic grains within the magnetic layer, while using a barrier layer to prevent this material from affecting the underlayer. This localized application of grain boundary material reduces exchange coupling between adjacent magnetic grains, thereby improving reliability while maintaining the small grain size necessary for high recording density.
3Reliability
If L10 type ordered alloy is used for high perpendicular magnetic anisotropy, then thermal stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent segments the layer structure by introducing a distinct NaCl-structured barrier layer between the magnetic layer and the underlayer. This segmentation allows the use of L10 type ordered alloy in the magnetic layer for high thermal stability while managing the complexity through a clear functional division: the barrier layer specifically addresses the ordering issue without requiring fundamental changes to the magnetic layer composition or structure.
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 proposed configuration enhances medium SNR and reduces coercivity distribution, achieving uniform crystal grain sizes and improved thermal stability, while maintaining the ordering of L10 type alloy crystal grains, thus supporting higher recording densities and better write characteristics in magnetic storage apparatuses.
Implementation Method 1
a barrier layer made of a material having an NaCl structure, wherein the plurality of underlayers include at least one crystalline underlayer including Mo as a main component
Implementation Method 2
the L10 type ordered alloy within the magnetic layer preferably has a good (001) orientation. Because the orientation of the magnetic layer can be controlled by an underlayer
Implementation Method 3
The heat-assisted recording method performs recording with respect to a magnetic recording medium using a magnetic head mounted with a laser light source, by heating the magnetic recording medium by the magnetic head
Implementation Method 4
the magnetic layer is added with a grain boundary material, such as an oxide including SiO2, TiO2, or the like, or C, BN, or the like. By employing a granular structure in which the magnetic crystal grains are separated at the grain boundary, an exchange coupling between the magnetic grains is reduced
Data Source
AI summary
A magnetic recording medium includes a substrate, a magnetic layer including an alloy having an L10 type crystal structure as a main component thereof, a plurality of underlayers arranged between the substrate and the magnetic layer, and a barrier layer made of a material having an NaCl structure. The plurality of underlayers include at least one crystalline underlayer including Mo as a main component thereof, and at least one of Si and C in a range of 1 mol % to 20 mol % and an oxide in a range of 1 vol % to 50 vol %. The barrier layer is provided between the magnetic layer and the at least one crystalline underlayer including Mo.