Perpendicular Magnetic Recording Disk Template Layer Nanoparticles
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Solution Overview
Problem
Current continuous-media perpendicular magnetic recording disks with granular cobalt-alloy recording layers suffer from irregular grain size distribution and random grain location, leading to variations in magnetic recording properties and signal-to-ratio loss due to large intergranular exchange fluctuations.
Innovation Solution
A template layer with nanoparticles embedded in a polymer material is used to control nucleation sites, allowing for the growth of granular Co alloy grains with a hexagonal-close-packed structure and intergranular oxides, resulting in a more uniform grain size and location distribution, achieved through the use of a seed layer and Ru or Ru alloy underlayer that promotes perpendicular magnetic anisotropy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional continuous-media perpendicular magnetic recording disks with granular cobalt-alloy recording layers are used, then magnetic recording capability is achieved, but irregular grain size distribution and random grain location result in variations in magnetic recording properties and signal-to-ratio loss
Solution Approach 1:
A template layer comprising nanoparticles spaced-apart and partially embedded within a polymer material is formed on the substrate before depositing the recording layer. The nanoparticles protrude above the polymer material surface to serve as predetermined nucleation sites, controlling the location and size of magnetic grains before the actual recording layer formation occurs. This preliminary structuring ensures uniform grain distribution and eliminates random grain locations.
Solution Approach 2:
The template layer with spaced-apart nanoparticles acts as an intermediary between the substrate and the granular cobalt-alloy recording layer. This intermediate structure provides controlled nucleation sites that mediate the formation of the recording layer, ensuring uniform grain size and location without directly becoming part of the magnetic recording medium itself.
2Reliability
If oxide segregants are added to enhance grain segregation in the cobalt alloy recording layer, then intergranular exchange coupling is reduced, but grain size distribution becomes irregular and thermal stability may be compromised
Solution Approach 1:
The template layer with uniformly spaced nanoparticles is formed before depositing the cobalt alloy recording layer with oxide segregants. This preliminary structure controls nucleation sites and grain growth, ensuring that even with oxide addition, the grains maintain uniform size and distribution while achieving adequate intergranular decoupling.
Solution Approach 2:
The template layer creates local control over grain formation at each nanoparticle site, while the oxide segregants provide global decoupling effects. The localized nucleation control compensates for the potential grain size variations that might result from oxide segregation, maintaining both intergranular decoupling and grain uniformity.
3Stability of the object's composition
If ruthenium underlayers are used to induce perpendicular magnetic anisotropy, then c-axis orientation is achieved, but grain location remains random and size distribution is wide
Solution Approach 1:
The template layer with spaced-apart nanoparticles is formed on the substrate before depositing the ruthenium underlayer and subsequent recording layers. The nanoparticles protrude through the ruthenium layer to serve as nucleation sites, controlling grain location while the ruthenium induces perpendicular magnetic anisotropy through its hcp crystal structure and c-axis orientation.
Solution Approach 2:
The template layer acts as an intermediary that controls grain nucleation and location, while the ruthenium underlayer serves as an intermediary for inducing perpendicular magnetic anisotropy. Both intermediaries work together to achieve controlled grain distribution with perpendicular magnetic properties.
Data Source
AI summary
A perpendicular magnetic recording disk includes a template layer below a Ru or Ru alloy underlayer, with a granular Co alloy recording layer formed on the underlayer. substrate. The template layer comprises nanoparticles spaced-apart and partially embedded within a polymer material, with the nanoparticles protruding above the surface of the polymer material. A seed layer covers the surface of the polymer material and the protruding nanoparticles and an underlayer of Ru or a Ru alloy covers the seed layer. The protruding nanoparticles serve as the controlled nucleation sites for the Ru or Ru alloy atoms. The nanoparticle-to-nanoparticle distances can be controlled during the formation of the template layer. This enables control of the Co alloy grain diameter distribution as well as grain-to-grain distance distribution.