HAMR Underlayer Composition for Coercivity and Grain Control
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Solution Overview
Problem
Current heat-assisted magnetic recording media face limitations in enhancing areal recording density due to insufficient coercivity, which can be attributed to inadequate crystal orientation and exchange coupling between magnetic grains.
Innovation Solution
A heat-assisted magnetic recording medium is developed with a layered structure comprising a substrate, a first underlayer containing magnesium oxide and additional compounds like vanadium oxide, zinc oxide, or vanadium nitride, and a second underlayer with a BCC or B2 structure, enhancing the (001) orientation and reducing exchange coupling between magnetic grains, thereby increasing coercivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the areal recording density is enhanced by making magnetic grains finer and reducing exchange coupling, then the coercivity increases, but the thermal stability may deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the underlayer by incorporating specific compounds (RuO2, IrO2, Rh, Ir, Os, or Re) with controlled content ratios. This compositional parameter change optimizes the interaction between the underlayer and magnetic layer, enabling finer magnetic grains while maintaining sufficient thermal stability through enhanced crystal orientation and controlled exchange coupling.
Solution Approach 2:
The patent creates a composite underlayer structure by combining magnesium oxide with additional compounds (RuO2, IrO2, Rh, Ir, Os, or Re). This composite material approach allows the underlayer to simultaneously provide crystal orientation promotion and controlled exchange coupling effects, resolving the contradiction between grain refinement and thermal stability maintenance.
2Manufacturing precision
If the crystal orientation of the magnetic layer is enhanced to increase coercivity, then the areal recording density improves, but the device complexity increases
Solution Approach 1:
The patent applies local quality by creating a specialized underlayer with specific compositional characteristics that locally promote (001) crystal orientation in the magnetic layer. The underlayer contains magnesium oxide combined with specific compounds (RuO2, IrO2, Rh, Ir, Os, or Re) at controlled ratios, providing localized crystal orientation promotion without requiring complex overall device structure.
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 enhances the coercivity of the magnetic recording medium, allowing for improved areal recording density by promoting finer magnetic grain growth and reduced exchange coupling, leading to higher thermal stability and recording performance.
Implementation Method 1
the (100) plane of MgO lattice-matches the (001) plane of a FePt alloy having an L10 structure
Implementation Method 2
a surface is locally heated by irradiating a magnetic recording medium with near-field light
Implementation Method 3
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. The substrate, the underlayer, and the magnetic layer are stacked in the recited order. The underlayer includes a first underlayer. The first underlayer includes magnesium oxide and one or more compounds selected from the group consisting of vanadium oxide, zinc oxide, tin oxide, vanadium nitride, and vanadium carbide, and a total content of the one or more compounds is in a range of 45 mol % to 70 mol %.