Magnetic Recording Medium Grain Size Control
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Solution Overview
Problem
It is challenging to simultaneously maintain satisfactory (001) orientation of the magnetic layer with an L10 crystal structure and reduce the size of magnetic grains in magnetic recording media while achieving high recording density.
Innovation Solution
A magnetic recording medium structure comprising a substrate, a barrier layer, a crystal grain size control layer with Ag, and a magnetic layer with an L10 crystal structure, where the barrier layer contacts the crystal grain size control layer, allowing Ag to form point-like precipitates that facilitate lattice matching and nucleus generation density, thereby maintaining orientation and reducing grain size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnetic layer with L10 crystal structure is used to achieve high perpendicular magnetic anisotropy, then (001) orientation is maintained, but magnetic grain size cannot be sufficiently reduced
Solution Approach 1:
The patent segments the magnetic layer into discrete magnetic grains with controlled size and distribution. By forming a granular structure where magnetic grains are separated by non-magnetic regions, the patent achieves both sufficient grain size reduction for high density and maintains the L10 crystal structure for high magnetic anisotropy. The grain size is controlled to be 5-20 nm while preserving the (001) orientation through careful microstructure design.
Solution Approach 2:
The patent applies local quality by creating regions with different compositions and structures within the magnetic layer. The magnetic grains have L10 crystal structure with high magnetic anisotropy, while the inter-grain regions have different properties that prevent grain growth. This local differentiation allows small grain sizes to be maintained without compromising the overall magnetic anisotropy of the layer.
2Productivity
If magnetic grain size is reduced to increase recording density, then storage capacity improves, but (001) orientation of the magnetic layer deteriorates
Solution Approach 1:
The patent applies preliminary action by forming a seed layer or underlayer with predetermined crystal orientation before depositing the magnetic layer. This underlayer is prepared in advance with the correct (001) orientation, which then templates and guides the crystal growth of the subsequent magnetic layer. This preliminary structural preparation ensures that even when magnetic grains are reduced to 5-20 nm for high density, the (001) orientation is maintained throughout the magnetic layer.
3Reliability
If high-Ku material is used to reduce magnetic grain volume, then thermal instability is maintained, but manufacturing complexity increases
Solution Approach 1:
The patent uses composite materials by combining the high-Ku L10 crystal structure magnetic layer with non-magnetic spacer layers or capping layers. This composite structure allows the magnetic layer to maintain high thermal stability through the L10 structure while the additional layers provide structural support and control grain growth. The composite approach manages the complexity by creating a multi-layer system where each layer has a specific function, making the overall structure controllable and manufacturable.
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 structure effectively maintains satisfactory (001) orientation and reduces the size of magnetic grains, improving recording density and signal-to-noise ratio in heat-assisted magnetic recording media.
Implementation Method 1
Ag to form point-like precipitates that facilitate lattice matching and nucleus generation density
Data Source
AI summary
A magnetic recording medium includes a substrate, a barrier layer, a crystal grain size control layer, and a magnetic layer that are arranged in this order. The barrier layer includes at least one of oxides, nitrides, and carbides, and the crystal grain size control layer is a crystalline layer including Ag and having an average thickness in a range of 0.1 nm to 1 nm. The barrier layer makes contact with the crystal grain size control layer, and the magnetic layer includes an alloy having a L10 crystal structure and a (001) face orientation.