TiO2 Underlayer for FePt Magnetic Recording Media
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Solution Overview
Problem
Current magnetic recording media face challenges in achieving sufficient improvement in Signal-to-Noise Ratio (SNR) despite using high-Ku materials like L10 type FePt alloys with (001) orientation, which is essential for high perpendicular magnetic anisotropy.
Innovation Solution
A magnetic recording medium is designed with a substrate, a magnetic layer of L10 type FePt alloy, and multiple underlayers, where at least one underlayer includes TiO2, applying tensile stress to optimize the (001) orientation of the FePt alloy, promoting atomic ordering and reducing coercivity variance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If L10 type FePt alloy with (001) orientation is used for the magnetic layer, then perpendicular magnetic anisotropy is improved, but medium SNR is insufficient
Solution Approach 1:
The patent changes the physical parameters of the underlayer by introducing TiO2 with specific crystal orientations ((100) or (110)) and controlling its lattice constant. This parameter change in the underlayer's crystal structure and orientation induces tensile stress that improves the (001) orientation of the FePt magnetic layer, thereby enhancing both perpendicular magnetic anisotropy and medium SNR simultaneously
Solution Approach 2:
The patent employs a composite underlayer structure combining TiO2 with other materials (such as Ru, Rh, Ir, or their alloys) to create a multi-component system. This composite underlayer provides both the necessary tensile stress through TiO2's lattice characteristics and additional functional properties that contribute to improved magnetic layer orientation and reduced coercivity variance, resolving the contradiction between anisotropy and SNR
2Measurement precision
If grain boundary material is added to separate crystal grains, then medium SNR is improved, but coercivity variance increases
Solution Approach 1:
The patent changes the stress state parameter in the magnetic layer by using TiO2 underlayer with controlled crystal orientation. The tensile stress induced by the TiO2 underlayer's lattice constant modifies the magnetic anisotropy energy landscape, leading to more uniform coercivity distribution across grain boundaries while maintaining the grain-separated structure necessary for high SNR
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 medium SNR by improving the ordering of the FePt alloy and reducing the normalized coercivity variance, leading to higher coercivity and better magnetic recording performance.
Implementation Method 1
at least a first underlayer amongst the plurality of underlayers includes TiO2... applying tensile stress to optimize the (001) orientation of the FePt alloy
Implementation Method 2
The microwave-assisted recording method performs recording on the magnetic recording medium by applying a high-frequency magnetic field of 10 GHz or higher from the magnetic head
Implementation Method 3
The heat-assisted recording method performs recording with respect to a magnetic recording medium using a magnetic head mounted with a laser diode, by heating the magnetic recording medium by the magnetic head
Data Source
AI summary
A magnetic recording medium includes a substrate, a magnetic layer including a FePt alloy having a L10 type structure, and a plurality of underlayers arranged between the substrate and the magnetic layer, wherein at least one of the plurality of underlayers includes TiO2.