Perpendicular Magnetic Recording Medium Seed Layer Segmentation
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Solution Overview
Problem
Existing perpendicular magnetic recording media face challenges in achieving high recording density due to limitations in the component and composition of laminated layers and their sequence, resulting in both merits and demerits in performance.
Innovation Solution
A perpendicular magnetic recording medium is designed with a specific lamination structure comprising a soft magnetic underlayer, two seed layers with precise material compositions and thicknesses, a granular magnetic recording layer, a non-granular magnetic recording layer, a protective layer, and a lubricant layer on a nonmagnetic substrate, optimized for alignment and electromagnetic conversion performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single seed layer is used in perpendicular magnetic recording medium, then the structure is simpler, but the orientation alignment and recording density performance are insufficient
Solution Approach 1:
The single seed layer is segmented into two distinct seed layers with different material compositions and functions. The first seed layer (CoFeB) provides initial crystalline nucleation and orientation control, while the second seed layer (CoFe) enhances magnetic properties and further refines orientation alignment. This segmentation resolves the contradiction by achieving superior orientation alignment through functional division while maintaining reasonable structural complexity.
Solution Approach 2:
The patent employs composite material structure with two seed layers having different material compositions (CoFeB and CoFe). This composite approach allows each layer to contribute its unique properties - CoFeB provides excellent crystalline structure and orientation control, while CoFe enhances magnetic moment and magnetic properties. The composite material strategy achieves high orientation alignment and recording density while managing overall structural complexity.
2Quantity of substance
If the magnetic layer has fine crystal grains for high recording density, then the recording density increases, but the grain isolation and orientation control become more difficult
Solution Approach 1:
The patent introduces a nonmagnetic intermediate layer (Ru) between the soft magnetic underlayer and the magnetic recording layer. This intermediary layer serves as a buffer that promotes fine grain formation while maintaining grain isolation through its nonmagnetic properties. The Ru layer also provides template effect for crystalline orientation control, enabling high recording density with proper grain isolation and orientation control simultaneously.
Solution Approach 2:
The patent applies different material properties and compositions to different regions and layers. The seed layers have specific compositions optimized for nucleation and orientation, the intermediate layer provides isolation and template effects, and the magnetic recording layer has composition optimized for fine grains. This local quality differentiation enables simultaneous achievement of fine grains for high density while maintaining grain isolation and orientation control.
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 proposed structure achieves high recording density with improved orientation alignment and signal-to-noise ratio, effectively addressing the limitations of previous technologies by controlling grain size and orientation dispersion, thereby enhancing electromagnetic conversion characteristics.
Implementation Method 1
The soft magnetic underlayer sharply draws in the magnetic field generated by a magnetic head and decreases gradient of the magnetic field
Implementation Method 2
the recording bits recorded on the perpendicular magnetic recording medium have more stable remnant magnetization at a higher recording density owing to the effect of a demagnetizing field from adjacent recording bits
Implementation Method 3
The recording lamination body is formed by epitaxial growth over the seed layers through the nonmagnetic intermediate layer
Data Source
AI summary
A magnetic recording medium exhibiting a high recording density performance is disclosed. The perpendicular magnetic recording medium has a soft magnetic underlayer, a first seed layer, a second seed layer, an intermediate layer, a granular magnetic recording layer, a non-granular magnetic recording layer, a protective layer, and a lubricant layer laminated on a nonmagnetic substrate in this order. The first seed layer contains cobalt, nickel, and at least one element selected from a group consisting of Si, Cr, V, Zr, Nb, Ta, Ti, Cu, and Mo, and the second seed layer contains nickel, chromium, and at least one element selected from a group consisting of Si, V, Zr, Nb, Ta, Ti, Cu, and Mo.