Magnetic Seed Layer Enhances Writability in Hard Disk Media
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Solution Overview
Problem
Conventional magnetic recording media with non-magnetic seed layers face limitations in writability and signal-to-noise ratio due to the distance between the magnetic recording head and the top soft underlayer, which can be improved by using a magnetic seed layer to enhance magnetic coupling and reduce the physical thickness of the soft underlayer.
Innovation Solution
Incorporating a magnetic seed layer with a crystalline structure, alloyed with Nickel and other magnetic materials, above the unbalanced soft underlayer structure to facilitate columnar grain growth and improve magnetic coupling, thereby reducing the distance between the magnetic recording head and the soft underlayer, and optimizing the thickness and composition of the magnetic seed layer to match the magnetic properties of the soft underlayer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a non-magnetic seed layer is used, then the structure is simpler and easier to manufacture, but the writability and signal-to-noise ratio deteriorate due to increased distance between the magnetic recording head and the soft underlayer
Solution Approach 1:
The patent changes the magnetic property parameter of the seed layer from non-magnetic to magnetic (specifically, using a magnetic seed layer with saturation magnetization Ms between 500-2000 emu/cm³). This parameter change enables the seed layer to provide magnetic coupling with the soft underlayer, improving writability and signal-to-noise ratio while maintaining manufacturing simplicity
Solution Approach 2:
The patent creates a composite magnetic structure by combining the magnetic seed layer with the soft underlayer (SUL). The magnetic seed layer acts as an intermediate magnetic coupling layer between the magnetic recording layer and the SUL, forming a composite magnetic circuit that enhances flux conductance and improves recording performance
2Length of moving object
If the soft underlayer thickness is reduced to improve writability, then the distance to the magnetic recording head decreases, but the effective magnetic thickness may be insufficient without compromising overwrite properties
Solution Approach 1:
The magnetic seed layer serves as an intermediary magnetic coupling layer between the magnetic recording layer and the soft underlayer. It provides the necessary magnetic coupling to maintain effective magnetic thickness and overwrite properties while allowing the physical soft underlayer thickness to be reduced, thereby decreasing the distance to the magnetic recording head and improving writability
Solution Approach 2:
The patent segments the magnetic circuit function into two parts: the magnetic seed layer provides the coupling interface close to the recording head for improved writability, while the soft underlayer maintains its role in providing magnetic flux return path for overwrite properties. This functional segmentation allows optimization of both writability and overwrite performance
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 magnetic seed layer enhances writability and signal-to-noise ratio by reducing the physical thickness of the soft underlayer while maintaining or increasing its effective magnetic thickness, improving performance at higher recording densities and reducing track width without sacrificing overwrite properties.
Implementation Method 1
Incorporating a magnetic seed layer with a crystalline structure, alloyed with Nickel and other magnetic materials, above the unbalanced soft underlayer structure to facilitate columnar grain growth
Implementation Method 2
The magnetic seed layer enhances writability and signal-to-noise ratio by reducing the physical thickness of the soft underlayer while maintaining or increasing its effective magnetic thickness
Data Source
AI summary
A magnetic media is described including a substrate, an unbalanced soft under layer (SUL), a magnetic seed layer, which may consist of one or more of NiWxCoy, NiWxCoyAlz, NiVaCob, NiVaCobAlc, NiWxVaCob, and NiWxVaFeb, and a magnetic recording layer.