FePt Granular Magnetic Recording Layer With Oxygen-Blocking Grain Boundaries
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Solution Overview
Problem
Existing methods struggle to form a stable FePt-hBN granular magnetic layer due to oxygen diffusion from the substrate, leading to coarsening of magnetic grains and deterioration of magnetic properties, which hinders the improvement of surface recording density in magnetic recording media.
Innovation Solution
A magnetic recording medium with a layered structure comprising a first magnetic layer with aluminum nitride at the grain boundary and a second magnetic layer with hexagonal boron nitride, preventing oxygen diffusion by using aluminum nitride to capture oxygen atoms, thereby maintaining grain size and enhancing saturation magnetization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional sputtering method is used to form FePt-hBN granular magnetic layer, then hexagonal boron nitride can be formed with high energy density plasma, but oxygen atoms diffuse into the magnetic layer causing grain coarsening and deterioration of magnetic properties
Solution Approach 1:
The patent introduces an aluminum nitride layer as an intermediary between the oxygen-containing environment and the FePt-hBN magnetic layer. This aluminum nitride barrier layer prevents oxygen atoms from diffusing into the magnetic layer during high-energy plasma processing, thereby eliminating the harmful effect of oxygen diffusion while maintaining the benefits of hexagonal boron nitride formation.
Solution Approach 2:
The patent applies preliminary action by forming the aluminum nitride barrier layer before introducing oxygen-containing species or applying high-energy plasma. This preliminary protective layer is prepared in advance to prevent oxygen diffusion before the harmful process occurs, ensuring the magnetic layer remains free from oxygen contamination throughout subsequent processing steps.
2Manufacturing precision
If hexagonal boron nitride is formed using high energy plasma, then grain boundary formation is achieved, but oxygen diffusion causes coarsening of FePt grains and deterioration of saturation magnetization
Solution Approach 1:
The aluminum nitride layer serves as a protective intermediary that allows high-energy plasma processing to occur without oxygen diffusion into the magnetic layer. This enables precise grain boundary formation through hexagonal boron nitride while the aluminum nitride barrier maintains saturation magnetization stability by blocking oxygen from reaching the FePt grains.
Solution Approach 2:
The patent applies local quality by creating distinct regions with different functions: the aluminum nitride barrier layer provides oxygen protection specifically at the interface, while the FePt-hBN magnetic layer maintains its magnetic properties and grain boundary structure. Each layer has localized properties optimized for its specific function.
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 solution effectively prevents grain coarsening and maintains high saturation magnetization, thereby improving the surface recording density and electromagnetic conversion characteristics of the magnetic recording medium.
Implementation Method 1
preventing oxygen diffusion by using aluminum nitride to capture oxygen atoms
Implementation Method 2
hexagonal boron nitride (hBN) at a grain boundary portion... it is possible to reduce a grain diameter (or a grain size) of the FePt magnetic grains
Implementation Method 3
Heat assisted recording systems or microwave assisted recording systems perform recording at a reduced coercivity by locally heating a magnetic recording medium by irradiating near-field light or microwave
Data Source
AI summary
A magnetic recording medium includes a nonmagnetic substrate, an underlayer disposed above the nonmagnetic substrate, and a magnetic recording layer disposed above the underlayer. The magnetic recording layer includes a first magnetic layer disposed above the underlayer, and a second magnetic layer disposed above the first magnetic layer. Each of the first magnetic layer and the second magnetic layer has a granular structure including magnetic grains having a L10 structure and a grain boundary portion. The grain boundary portion of the first magnetic layer includes aluminum nitride, and the grain boundary portion of the second magnetic layer includes hexagonal boron nitride. An aluminum nitride content in the first magnetic layer is in a range of 15 vol % to 35 vol %, and a peak in a B1s spectrum of the grain boundary portion of the second magnetic layer observed using X-ray photoelectron spectroscopy is 191.6 eV or less.