Onset Magnetic Oxide Layer for Perpendicular Recording Media
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Solution Overview
Problem
Perpendicular magnetic recording media face challenges in achieving high track density and resolution due to the broadening of the write width and poor resolution, which are linked to the capping structure and magnetic grain separation, necessitating improved coercivity and signal-to-noise ratio.
Innovation Solution
An onset magnetic oxide layer is introduced, sputter-deposited in an argon-oxygen gas mixture between the main magnetic oxide layers and underlayers, enhancing coercivity and nucleation field, and improving magnetic isolation between grains, using alloys with specific compositions and thicknesses to optimize recording properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If exchange interaction between grains is increased to improve on-track performance, then recording performance is improved, but write width broadens which limits track density
Solution Approach 1:
The magnetic layer is segmented into multiple functional layers: a granular magnetic layer with isolated grains for high resolution, an exchange coupling layer for mediating interaction, and a capping layer for stability. This segmentation allows each layer to be optimized independently - the granular layer maintains narrow write width while the capping layer provides the necessary exchange interaction for on-track performance.
Solution Approach 2:
An exchange coupling layer is introduced as an intermediary between the granular magnetic layer and the capping layer. This intermediate layer mediates the exchange interaction, allowing the granular layer to maintain its isolated grain structure for high resolution while still achieving sufficient exchange coupling for on-track performance through the mediator layer.
2Reliability
If capping structure is used to improve stability and media noise, then recording performance is improved, but resolution deteriorates
Solution Approach 1:
The magnetic structure is divided into a granular magnetic layer with physically isolated grains for high resolution and a separate capping layer for stability. The segmentation allows the granular layer to maintain sharp magnetic transitions for high resolution while the capping layer provides thermal stability and reduces media noise through its continuous structure.
Solution Approach 2:
Different regions of the magnetic structure have different properties: the granular layer has localized magnetic moments with strong anisotropy for high resolution, while the capping layer has continuous exchange coupling for stability. The local quality of each layer is optimized for its specific function - resolution in the granular layer and stability in the capping layer.
3Reliability
If magnetic grain separation is increased to improve coercivity and SNR, then recording performance is improved, but initial growth control becomes more critical
Solution Approach 1:
An underlayer is deposited beforehand to prepare the substrate surface before depositing the granular magnetic layer. This preliminary action creates a controlled interface that promotes uniform nucleation and initial growth of magnetic grains, ensuring consistent grain separation and distribution. The underlayer pre-establishes the conditions needed for optimal grain isolation and magnetic properties.
Solution Approach 2:
The composition and thickness of the underlayer are carefully controlled to modify the growth parameters of the subsequent magnetic layer. By adjusting the underlayer properties, the initial growth rate, grain size, and separation of the magnetic layer can be optimized to achieve the desired coercivity and signal-to-noise ratio while maintaining manufacturable precision.
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 onset magnetic oxide layer significantly enhances coercivity, nucleation field, and signal-to-noise ratio, leading to improved recording performance and reduced bit error rate, particularly at optimal thicknesses of 1-3 nm, thereby addressing the limitations of existing perpendicular recording systems.
Implementation Method 1
The invention uses an onset magnetic oxide layer that may be sputter deposited in an argon-oxygen gas mixture between the main magnetic oxide layer(s) and the underlayer(s)
Data Source
AI summary
Perpendicular magnetic recording media has been enhanced by controlling the initial growth of magnetic oxide layers and increased magnetic isolation between the grains in the initial magnetic layer. An onset magnetic oxide layer is sputter deposited in an argon-oxygen gas mixture between the main CoPtCr-oxide magnetic layers and the underlying Ru layer. The insertion of the onset magnetic oxide layer enhances the coercivity of the oxide magnetic layers and also improves the nucleation field. The media signal-to-noise ratio and bit error rate also are significantly improved due to the improvement of the initial segregation of Co magnetic grains in the magnetic oxide layers.