Magnetic Recording Medium Seed Layer for High Density Thermal Stability
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Solution Overview
Problem
Current magnetic recording media face challenges in achieving high recording density while maintaining thermal stability, as reducing magnetic crystal grain diameter decreases thermal stability, and forming granular structures with L10 ordered alloys on MgO seed layers is difficult.
Innovation Solution
A magnetic recording medium with a seed layer of NaCl-type, spinel-type, or perovskite-type compounds, where the magnetic recording layer consists of a continuous first magnetic layer and a granular second magnetic layer with ordered alloys and non-magnetic oxide crystal grain boundaries, enhancing separation and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
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 decreases
Solution Approach 1:
The patent changes the material composition parameter by using L10 ordered alloys (FePt, CoPt, FePd, CoPd) with high magnetocrystalline anisotropy constants. This parameter change allows maintaining thermal stability even when grain diameter is reduced to 5 nm or less, thereby enabling high recording density while preserving reliability.
Solution Approach 2:
The patent creates a composite granular structure consisting of magnetic crystal grains (L10 ordered alloy) and non-magnetic crystal grain boundaries (oxide materials). This composite structure provides both high recording density through small grain size and high thermal stability through the magnetic properties of the L10 ordered alloy grains.
2Reliability
If L10 ordered alloys are used to maintain thermal stability with reduced grain diameter, then thermal stability is improved, but formation of granular structure on MgO seed layers becomes difficult
Solution Approach 1:
The patent introduces an interlayer between the MgO seed layer and the magnetic recording layer containing L10 ordered alloys. This interlayer acts as a mediator that facilitates the formation of granular structures with L10 ordered alloys on MgO seed layers, overcoming the previously observed formation difficulties.
Solution Approach 2:
The patent changes the structural parameters by implementing a multi-layer configuration with specific layer thicknesses and compositions. The interlayer has controlled thickness and composition parameters that enable proper epitaxial growth and granular structure formation of L10 ordered alloys on MgO substrates.
3Ease of manufacture
If conventional magnetic recording layers are formed on MgO seed layers, then manufacturing is simplified, but granular structure quality and perpendicular-to-plane coercive force are insufficient
Solution Approach 1:
The patent creates a composite multi-layer structure consisting of MgO seed layer, interlayer, and magnetic recording layer with L10 ordered alloys. This composite structure maintains ease of manufacture through standardized layer deposition while achieving high granular structure quality and perpendicular-to-plane coercive force through the specific combination of materials and their controlled interfaces.
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 results in a magnetic recording medium with improved perpendicular-to-plane coercive force and granular structure quality, overcoming the limitations of conventional layers formed on MgO seed layers.
Implementation Method 1
the magnetic crystal grains in the granular magnetic material need to be formed of a material with higher magnetocrystalline anisotropy, in order to compensate the decrease in thermal stability due to the reduction in the grain diameter
Implementation Method 2
Respective magnetic crystal grains in the granular magnetic material are magnetically separated from each other with the non-magnetic body
Data Source
AI summary
The invention provides a magnetic recording medium including a magnetic layer or a magnetic recording layer having a granular structure in which magnetic crystal grains are well separated from each other. The magnetic recording medium includes a substrate, a seed layer, and a magnetic recording layer, wherein the magnetic recording layer includes a first magnetic layer which is a continuous film consisting of an ordered alloy, and a second magnetic layer having a granular structure consisting of magnetic crystal grains consisting of an ordered alloy and a non-magnetic crystal grain boundary, and the seed layer consists of a material selected from the group consisting of an NaCl-type compound, a spinel-type compound, and a perovskite-type compound.