HAMR Medium Bcc Underlayer MgO Orientation
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Solution Overview
Problem
Current heat-assisted magnetic recording media face limitations in enhancing areal recording density and electromagnetic conversion characteristics, particularly in achieving optimal crystal orientation and reducing exchange coupling between magnetic grains.
Innovation Solution
A heat-assisted magnetic recording medium is developed with a layered structure comprising a substrate, a bcc underlayer, a first oxide layer with magnesium oxide, and a second oxide layer containing vanadium oxide, nitride, or carbide, which enhances the (001) orientation of the magnetic layer and reduces exchange coupling by promoting finer magnetic grain growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a FePt alloy having an L10 structure is used as the magnetic layer to enhance electromagnetic conversion characteristics, then the crystal orientation must be (001) oriented requiring (100) oriented MgO underlayer, but this restricts the choice of underlayer materials and complicates the layer structure design
Solution Approach 1:
The patent introduces a bcc underlayer as an intermediary between the substrate and the MgO layer. This bcc underlayer serves as a mediator that facilitates the formation of (100) oriented MgO, which in turn enables (001) orientation of the FePt magnetic layer. The bcc underlayer acts as a structural bridge that simplifies the overall alignment requirements.
Solution Approach 2:
The patent employs a composite underlayer structure consisting of a bcc crystal structure layer combined with MgO layers. This composite approach allows the system to achieve the desired (001) orientation of the magnetic layer while providing flexibility in material selection and reducing the complexity of achieving perfect lattice matching throughout the entire structure.
2Productivity
If magnetic grains are made finer to reduce exchange coupling and enhance areal recording density, then the electromagnetic conversion characteristics improve, but the manufacturing precision and control of grain size become more difficult
Solution Approach 1:
The patent utilizes parameter changes in the underlayer structure, specifically the crystal orientation and composition of the bcc underlayer and MgO layers, to control the nucleation and growth of magnetic grains. By adjusting the orientation relationships and material parameters in the underlayer, the patent achieves finer and more uniform magnetic grain sizes without requiring extremely precise manufacturing controls.
3Productivity
If the crystal orientation of the magnetic layer is enhanced to improve electromagnetic conversion characteristics, then the areal recording density increases, but the thermal stability requirements become more stringent
Solution Approach 1:
The patent implements preliminary action by establishing the proper crystal orientation in the underlayer (bcc and MgO layers) before depositing the magnetic layer. This pre-established orientation framework ensures that the magnetic layer forms with the desired (001) orientation, which simultaneously achieves high areal recording density and maintains thermal stability through proper magnetic anisotropy alignment.
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 structure significantly improves electromagnetic conversion characteristics by enhancing the (001) orientation of the magnetic layer and reducing exchange coupling, leading to higher areal recording density and thermal stability.
Implementation Method 1
the (100) plane of MgO lattice-matches the (001) plane of a FePt alloy having an L10 structure
Implementation Method 2
enhance the crystal orientation of the magnetic layer
Implementation Method 3
reducing exchange coupling between the magnetic grains
Implementation Method 4
a surface is locally heated by irradiating a magnetic recording medium with near-field light
Implementation Method 5
writing on the magnetic recording medium is performed by reducing the magnetic coercivity of the magnetic recording medium
Data Source
AI summary
A heat-assisted magnetic recording medium includes: a substrate; an underlayer; and a magnetic layer including an alloy having an L10 structure, wherein the underlayer includes, from the substrate side, a bcc underlayer including a substance having a bcc structure, a first oxide layer that is in contact with the bcc underlayer, and a second oxide layer that is in contact with the magnetic layer. The bcc underlayer, the first oxide layer, and the second oxide layer are stacked in the recited order. The first oxide layer and the second oxide layer include magnesium oxide, and the second oxide layer further includes one or more compounds selected from the group consisting of vanadium oxide, vanadium nitride, and vanadium carbide.