Perpendicular Magnetic Recording Medium Underlayer Design
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Solution Overview
Problem
Current perpendicular magnetic recording media face challenges in achieving higher recording density due to deterioration of crystal orientation of the intermediate layer when microcrystallizing the NiW underlayer, which affects the overall recording performance.
Innovation Solution
A 2-layer underlayer structure is introduced, comprising a TiV alloy with an amorphous structure as the first underlayer and an NiW alloy with added elements like Co, Cu, Al, or Cr as the second underlayer, stacked on a soft magnetic underlayer, to improve crystal orientation and microcrystallization of the intermediate and perpendicular magnetic recording layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the NiW underlayer is microcrystallized to reduce crystal grain size, then the recording density is improved, but the crystal orientation of the intermediate layer deteriorates
Solution Approach 1:
The underlayer is divided into two distinct layers: a first underlayer made of TiV alloy and a second underlayer made of NiW alloy. This segmentation allows each layer to perform its specific function independently - the TiV layer provides amorphous structure for grain refinement while the NiW layer provides fcc structure for crystal orientation, thus resolving the contradiction between reducing grain size and maintaining crystal orientation.
Solution Approach 2:
The TiV alloy layer acts as an intermediary between the soft magnetic underlayer and the NiW alloy layer. It mediates the crystal growth process by providing an amorphous structure that promotes fine grain formation in the NiW layer without disrupting the overall crystal orientation needed for the intermediate layer above it.
2Productivity
If the crystal grain size of the underlayer is reduced to improve recording density, then the electromagnetic conversion characteristic is improved, but the crystal orientation control becomes difficult
Solution Approach 1:
By segmenting the underlayer into two functional layers with different material compositions and structures, the system achieves both fine crystal grain size (improving recording density) and controlled crystal orientation (maintaining manufacturing precision) simultaneously through the complementary properties of TiV and NiW alloys.
Solution Approach 2:
The dual-layer underlayer structure combines TiV alloy and NiW alloy to create a composite material system where each component contributes its unique properties - TiV provides amorphous structure for grain refinement while NiW provides fcc structure for orientation control, achieving both high recording density and precise crystal orientation.
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 enhances the crystal orientation, microcrystallization, and thermal conductivity of the NiW alloy, leading to improved electromagnetic conversion characteristics and increased recording density.
Implementation Method 1
the crystal grain size of the underlayer is reduced and improve the crystal orientation of the intermediate layer and the magnetic recording layer that are formed on the underlayer
Implementation Method 2
enhances the crystal orientation, microcrystallization, and thermal conductivity of the NiW alloy
Data Source
AI summary
A perpendicular magnetic recording medium includes a soft magnetic underlayer, an underlayer, an intermediate layer, and a perpendicular magnetic recording layer successively stacked on a nonmagnetic substrate. The soft magnetic underlayer includes a soft magnetic layer having an amorphous structure. The underlayer includes a first underlayer, and a second underlayer provided between the first underlayer and the intermediate layer. The first underlayer is made of a TiV alloy having an amorphous structure, and the second underlayer is made of an NiW alloy including at least one element selected from a group consisting of Co, Cu, Al, Cr, and Fe. The intermediate layer is made of Ru or an Ru alloy, and wherein the soft magnetic layer, the first underlayer, and the second underlayer are stacked in this order.