Magnetic Recording Medium Dual Ground Layer Crystal Orientation
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Solution Overview
Problem
Current magnetic recording media face challenges in achieving high recording capacity and signal-noise ratio due to limitations in crystal orientation characteristics and magnetic isolation, particularly in the composition and thickness of ground layers.
Innovation Solution
A magnetic recording medium with a layered structure comprising a recording layer, a first ground layer with a nonmagnetic oxide, and a second ground layer, where the first ground layer has a thickness of 2 nm to 10 nm and the second ground layer has a thickness of 40 nm or more, optimized with specific atomic ratios and materials like Co-based alloys and ruthenium, to enhance crystal orientation and suppress magnetic isolation loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-layer ground layer is used, then the structure is simple, but crystal orientation characteristics and magnetic isolation cannot be simultaneously optimized
Solution Approach 1:
The ground layer is divided into two distinct sub-layers: a first ground layer (2-10 nm thick) containing nonmagnetic oxide for optimizing crystal orientation, and a second ground layer (40 nm or more thick) for providing magnetic isolation. This segmentation allows each sub-layer to be independently optimized for its specific function, resolving the contradiction between performance and structural simplicity.
Solution Approach 2:
Different regions of the ground layer are assigned different materials and thicknesses to fulfill different functions. The first ground layer uses nonmagnetic oxide (such as RuO2, IrO2, or PtO2) with specific thickness (2-10 nm) to enhance crystal orientation, while the second ground layer uses magnetic shielding material (such as CoCrPt alloy) with greater thickness (40 nm or more) for magnetic isolation. This local differentiation enables simultaneous optimization of both crystal orientation and magnetic isolation.
2Reliability
If the first ground layer is made thinner to improve crystal orientation, then crystal orientation characteristics improve, but magnetic isolation deteriorates
Solution Approach 1:
The ground layer is segmented into two functional sub-layers with distinct thicknesses. The first ground layer is kept thin (2-10 nm) to maintain excellent crystal orientation characteristics, while the second ground layer is made thick (40 nm or more) to provide sufficient magnetic isolation. This segmentation resolves the contradiction by assigning different thickness requirements to different functional regions.
Solution Approach 2:
The first ground layer is designed with thin thickness (2-10 nm) and nonmagnetic oxide composition specifically for crystal orientation enhancement, while the second ground layer is designed with greater thickness (40 nm or more) and magnetic shielding material composition for magnetic isolation. This local quality differentiation allows each region to optimize its performance for its specific function without compromising the other.
3Loss of energy
If a thick ground layer is used to improve magnetic isolation, then magnetic isolation improves, but crystal orientation characteristics deteriorate
Solution Approach 1:
The ground layer is divided into two sub-layers with different thicknesses and compositions. The first ground layer (2-10 nm) contains nonmagnetic oxide to optimize crystal orientation, while the second ground layer (40 nm or more) provides magnetic isolation. This segmentation allows the thin first layer to maintain crystal orientation without being compromised by the thickness required for magnetic isolation in the second layer.
Solution Approach 2:
Different portions of the ground layer are assigned different materials and thicknesses: the first ground layer uses nonmagnetic oxide (RuO2, IrO2, PtO2) at 2-10 nm thickness for crystal orientation, while the second ground layer uses magnetic shielding material (CoCrPt alloy) at 40 nm or more thickness for magnetic isolation. This local quality approach enables each region to fulfill its specific function optimally.
4Quantity of substance
If recording density is increased to achieve high capacity, then recording capacity improves, but signal-noise ratio deteriorates
Solution Approach 1:
The patent employs a disposable-like approach by using a thin first ground layer (2-10 nm) of nonmagnetic oxide that can be easily deposited and provides optimal crystal orientation enhancement without requiring thick layers that would compromise signal-noise ratio. This thin layer achieves its function efficiently without introducing additional noise or complexity.
Solution Approach 2:
The ground layer uses composite material structure combining nonmagnetic oxide (such as RuO2, IrO2, or PtO2) in the first sub-layer with magnetic shielding material (such as CoCrPt alloy) in the second sub-layer. This composite structure enables simultaneous achievement of excellent crystal orientation characteristics and magnetic isolation, thereby maintaining high signal-noise ratio even at high recording densities of 100 Gb/in² or more.
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 configuration significantly improves crystal orientation and recording density, achieving a surface recording density of 100 Gb/in² or more, enabling large-capacity recording and maintaining high signal-noise ratio.
Implementation Method 1
This technique focuses on the fact that Ru has the same hexagonal close-packed structure as cobalt (Co) and this Ru has a lattice constant close to Co, devises crystal orientation of the Ru layer
Implementation Method 2
the recording layer contains a Co-based alloy particle, and X-ray relative intensity values of in-plane X-ray diffraction on a (11.0) plane and a (10.0) plane of the Co-based alloy particle may satisfy the following relational formula
Data Source
AI summary
An object is to provide a magnetic recording medium having favorable crystal orientation characteristics and exhibiting a high SNR.The present technology provides a magnetic recording medium having a layer structure including a recording layer, a ground layer, and a base layer in this order, in which the ground layer includes a first ground layer on the recording layer side and a second ground layer on the base layer side, the first ground layer contains a nonmagnetic oxide, the first ground layer has a thickness of 2 nm or more and 10 nm or less, and the second ground layer has a thickness of 40 nm or more. Furthermore, the present technology also provides a magnetic recording cartridge including the magnetic recording medium.