Magnetic Recording Medium MgO Underlayer Interdiffusion Control
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Solution Overview
Problem
The thermal assist recording method for magnetic recording media faces challenges in maintaining high (001) orientation of the magnetic layer due to interdiffusion between added elements and oxygen in the MgO underlayer, which deteriorates the crystal orientation and recording density.
Innovation Solution
A magnetic recording medium is developed with an upper underlayer represented by MgO(1-x), where x ranges from 0.07 to 0.25, and a first magnetic layer containing alloys with a L10 structure and elements like Al, Si, and Ge, deposited using a sputtering process with hydrogen-added inert gases to reduce interdiffusion and enhance (001) orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If elements such as Mg, Ni, Zn, Ge, Pd, Sn, Ag, Re, Au, or Pb are added to the magnetic layer to improve (001) orientation, then the crystal orientation is improved, but interdiffusion occurs between the added elements and oxygen in the MgO underlayer, generating oxides and deteriorating the (001) orientation
Solution Approach 1:
A non-oxidizable barrier layer is introduced between the magnetic layer and the MgO underlayer. This barrier layer acts as an intermediary that prevents oxygen diffusion from the MgO underlayer to the magnetic layer, thereby eliminating the interdiffusion issue while maintaining the beneficial (001) orientation enhancement from the added elements.
Solution Approach 2:
The patent employs a non-oxidizable material for the barrier layer that creates an inert environment for the magnetic layer, preventing oxidation reactions. This inert barrier allows the magnetic layer to maintain its composition stability while still achieving improved (001) orientation through the addition of elements like Ge, Pd, Sn, Ag, or Pb.
2Productivity
If the size of magnetic particles is reduced to 6 nm or less to improve electromagnetic conversion characteristics, then the recording density can be increased, but the thermal stability of magnetic information becomes more difficult to maintain
Solution Approach 1:
The patent utilizes high-Ku materials with enhanced magnetic anisotropy constants to change the magnetic parameters of the system. This allows smaller magnetic particles (6 nm or less) to maintain sufficient thermal stability by increasing the energy barrier for magnetic moment reversal, thereby enabling high recording density while preserving thermal stability.
Solution Approach 2:
The patent employs composite material structures including multiple layers (magnetic layer, barrier layer, underlayer) with different functional properties. The combination of high-Ku magnetic materials with the protective barrier layer creates a composite system that achieves both small particle size for high density and enhanced thermal stability through the synergistic effects of the composite 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
This approach improves the (001) orientation of the magnetic layer, stabilizes the crystal structure, and enhances the electromagnetic conversion characteristics, leading to increased surface recording density and magnetic signal strength.
Implementation Method 1
deposited using a sputtering process with hydrogen-added inert gases
Implementation Method 2
records magnetic information by locally heating the surface of the magnetic recording medium by irradiating near-field light or the like on the magnetic recording medium
Data Source
AI summary
A magnetic recording medium includes a substrate, an underlayer provided above the substrate, and a magnetic layer provided on and in contact with the underlayer. The underlayer includes a compound represented by a general formula MgO(1-x), where x falls within a range of 0.07 to 0.25. The magnetic layer includes an alloy having a L10 structure, and the alloy having the L10 structure includes one or more elements selected from a group consisting of Al, Si, Ga, and Ge.