Dual Phase MgO-X Seed Layers for HAMR Media Grain Alignment
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Solution Overview
Problem
In heat-assisted magnetic recording (HAMR) technology, the FePt magnetic recording layer grown on a single-phase MgO seed layer often results in irregularly shaped and non-uniformly sized grains due to surface energy mismatch, leading to poor recording performance and misaligned grains.
Innovation Solution
A dual-phase MgO-X seed layer is introduced, comprising small, uniformly sized MgO grains separated by a low surface energy segregant material, which aligns with the FePt layer to promote one-to-one grain growth and regular grain morphology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single-phase MgO seed layer is used, then the FePt layer can be grown, but the grains become irregularly shaped and non-uniformly sized due to surface energy mismatch
Solution Approach 1:
The patent uses a composite seed layer comprising both MgO and MgAl2O3 phases instead of pure MgO. The MgAl2O3 phase has different surface energy characteristics that complement MgO, enabling better matching with FePt layer surface energy. This composite structure produces uniform, regularly shaped FePt grains while maintaining excellent recording performance.
2Device complexity
If a single-phase MgO seed layer is used, then the structure is simple, but in-plane variants and misaligned grains occur in the FePt layer
Solution Approach 1:
The patent introduces local compositional variation within the seed layer by combining MgO and MgAl2O3 phases with different surface energy properties. This local quality differentiation allows specific regions of the seed layer to promote particular grain orientations, reducing in-plane variants and improving overall grain alignment in the FePt layer.
3Ease of manufacture
If a single-phase MgO seed layer is used, then the deposition process is simple, but thermal gradients are insufficient for optimal HAMR performance
Solution Approach 1:
The patent modifies the compositional parameters of the seed layer by incorporating MgAl2O3 alongside MgO. This compositional change alters the thermal conductivity and heat capacity of the seed layer, enabling enhanced thermal gradient formation during HAMR operation while maintaining compatibility with existing deposition processes.
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 dual-phase MgO-X seed layer improves the microstructure of the FePt layer, reducing in-plane variants and misaligned grains, enhancing thermal gradients, signal-to-noise ratios, and head lifetimes, while providing better manufacturability and corrosion resistance.
Implementation Method 1
surface energy mismatch, leading to poor recording performance and misaligned grains
Implementation Method 2
separated by a low surface energy segregant material, which aligns with the FePt layer to promote one-to-one grain growth
Data Source
AI summary
Magnetic media having dual phase MgO-X seed layers with both MgO grains and segregants are provided. One such magnetic medium includes a substrate, a heatsink layer on the substrate, a dual phase seed layer on the heatsink layer, where the dual phase seed layer comprises MgO and a segregant, where a concentration of the MgO is greater than 50 percent by volume in the dual phase seed layer, and a magnetic recording layer including FePt on the dual phase seed layer.