FePt Magnetic Layer Low-Temperature Ordering via Oxide Mediator
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Solution Overview
Problem
The challenge is to form an L10 structural FePt ordered alloy at a temperature equal to or below 300°C, as high temperature processes required for traditional methods exceed the temperature tolerance of structural materials used in hard disk devices.
Innovation Solution
A layered structure comprising an amorphous Ta layer, a metallic oxide layer formed from zinc oxide (ZnO) or magnesium oxide (MgO), and a FePt magnetic layer, where the FePt magnetic layer is annealed at a temperature of 200-300°C to achieve an L10 structural FePt ordered alloy with a coercive force of over 6,000 Oe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high temperature processes (over 500°C) are used to form L10 ordered structure, then the FePt alloy achieves the desired ordered structure and high coercive force, but the structural materials in hard disk devices cannot tolerate such high temperatures
Solution Approach 1:
A metallic oxide layer (ZnO or MgO) is introduced as an intermediary between the Ta layer and FePt magnetic layer. This intermediary layer enables the FePt alloy to form the L10 ordered structure at low temperatures (≤300°C) by facilitating atomic diffusion and ordering, while protecting the underlying structural materials from high temperature damage. The metallic oxide layer acts as a mediator that transforms the high-temperature ordering process into a low-temperature process.
Solution Approach 2:
The invention changes the key parameter of ordering temperature from high temperature (over 500°C) to low temperature (≤300°C) by introducing the metallic oxide layer. This parameter change is achieved through the specific interaction between the metallic oxide layer and FePt alloy, which lowers the energy barrier for atomic diffusion and ordering. The Ta layer thickness (≥2 nm) and metallic oxide layer thickness (≥2 nm) are also controlled as parameters to enable this low-temperature ordering process.
2Ease of manufacture
If traditional sputtering method is used to form FePt layer, then the layer can be formed, but it cannot be transformed into the ordered structure without high temperature annealing
Solution Approach 1:
The Ta layer and metallic oxide layer are formed in advance before the FePt magnetic layer. These preliminary layers are specifically designed to facilitate subsequent low-temperature ordering of the FePt alloy. The Ta layer (≥2 nm) serves as a diffusion barrier and template, while the metallic oxide layer (≥2 nm) provides the chemical environment necessary for low-temperature ordering. This preliminary preparation enables the FePt layer to be formed by simple sputtering and then transformed into the ordered structure at low temperature without requiring high-temperature annealing.
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 approach allows for the formation of a FePt magnetic layer with a high coercive force while maintaining the temperature limitations of structural materials, enabling its use in next-generation magnetic recording media and bias magnetic field applications.
Implementation Method 1
after the FePt magnetic layer is formed, it is annealed at a temperature equal to or below 300° C.
Implementation Method 2
a FePt layer, which is formed by a sputtering method, cannot be transformed (crystal-ordered) into the ordered structure because it does not pass through the ordered-random transformation point that exists at a high temperature
Implementation Method 3
the layered structure according to the present invention is provided to have the following structure: an amorphous Ta layer; a metallic oxide layer formed from one of zinc oxide (ZnO) and magnesium oxide (MgO) on the Ta layer; and a FePt magnetic layer formed on the metallic oxide layer
Data Source
AI summary
A layered structure includes an amorphous Ta layer, a metallic oxide layer formed from zinc oxide (ZnO) or magnesium oxide (MgO) on the Ta layer, and a FePt magnetic layer formed on the metallic oxide layer. Therefore, an L10 structural FePt ordered alloy is obtained at a temperature of 300° C. or lower.