Magnetic Recording Medium Underlayer Design for Heat-Assisted Recording
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Solution Overview
Problem
Conventional heat-assisted magnetic recording media face challenges in achieving sufficient (001) orientation of the magnetic layer, leading to inadequate signal-to-noise ratio (SNR) due to insufficient underlayer performance, which also fails to effectively control heat expansion and reduce noise.
Innovation Solution
A magnetic recording medium is designed with a substrate, a first underlayer composed of W, a second underlayer containing W with an oxide (2-30 mol %) such as WO3, and a magnetic layer with an L10 type crystal structure, where the second underlayer has a non-granular structure to enhance (001) orientation and suppress heat spot expansion, and a barrier layer with NaCl structure is included to prevent interfacial diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional underlayer is used to support the magnetic layer, then the magnetic layer can be formed, but the (001) orientation of the magnetic layer is insufficient leading to low signal-to-noise ratio
Solution Approach 1:
The underlayer is divided into two separate layers: a first underlayer containing W as main component and a second underlayer containing W and oxide. This segmentation allows each layer to perform specialized functions - the first underlayer provides foundational support while the second underlayer enhances (001) orientation and controls heat expansion, collectively improving the signal-to-noise ratio
Solution Approach 2:
The second underlayer uses a composite material containing W and oxide (2-30 mol%). This composite structure combines the beneficial properties of both materials - W provides crystalline structure and orientation control while the oxide component suppresses heat spot expansion. The specific composition range optimizes the balance between orientation enhancement and heat control, achieving high signal-to-noise ratio
2Reliability
If the underlayer material is optimized for (001) orientation, then the magnetic layer orientation improves, but heat spot expansion is not effectively suppressed
Solution Approach 1:
The underlayer is divided into two separate layers: a first underlayer containing W as main component and a second underlayer containing W and oxide. This segmentation allows each layer to perform specialized functions - the first underlayer provides foundational support while the second underlayer enhances (001) orientation and controls heat expansion, collectively improving the signal-to-noise ratio
Solution Approach 2:
The second underlayer uses a composite material containing W and oxide (2-30 mol%). This composite structure combines the beneficial properties of both materials - W provides crystalline structure and orientation control while the oxide component suppresses heat spot expansion. The specific composition range optimizes the balance between orientation enhancement and heat control, achieving high signal-to-noise ratio
3Device complexity
If a single-layer underlayer is used, then the structure is simple, but both (001) orientation enhancement and heat expansion control cannot be achieved simultaneously
Solution Approach 1:
The underlayer is divided into two separate layers: a first underlayer containing W as main component and a second underlayer containing W and oxide. This segmentation allows each layer to perform specialized functions - the first underlayer provides foundational support while the second underlayer enhances (001) orientation and controls heat expansion, collectively improving the signal-to-noise ratio
Solution Approach 2:
The two-layer underlayer structure performs multiple functions simultaneously: providing structural support, enhancing (001) orientation, and controlling heat spot expansion. The first underlayer handles foundational support while the second underlayer handles orientation enhancement and heat control, achieving multi-functionality that improves signal-to-noise ratio
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 significantly improves the signal-to-noise ratio (SNR) by enhancing the (001) orientation of the magnetic layer and effectively controlling heat expansion, resulting in reduced noise and increased recording density.
Implementation Method 1
the expansion of the heat spot needs to be suppressed such that a magnetic transition area is narrowed in a planar direction
Implementation Method 2
a magnetic head irradiates a magnetic recording medium with near-field light to partially heat the surface of the magnetic recording medium, such that the coercivity of the magnetic recording medium can be reduced
Data Source
AI summary
A magnetic recording medium includes: a substrate; a first underlayer; a second underlayer; and a magnetic layer including an alloy having a L10 type crystal structure with a (001) orientation. The substrate, the first underlayer the second underlayer, and the magnetic layer are stacked in this order. The first underlayer is a crystalline layer that includes W as a main component. The second underlayer is a crystalline layer that includes a material containing W as a main component and that includes an oxide. The content of the oxide in the second underlayer is in a range of from 2 mol % to 30 mol %. The oxide is an oxide of one or more kinds of elements selected from a group consisting of Cr, Mo, Nb, Ta, V, and W.