Ru-Modified FePt Alloy for Thermal Stability in Magnetic Recording
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Solution Overview
Problem
Current magnetic recording media face challenges in achieving high magnetic anisotropy constant Ku and low Curie temperature Tc, which limits the ability to write at lower heating temperatures while maintaining thermal stability of the written magnetization.
Innovation Solution
A magnetic recording medium with a magnetic recording layer containing an L10-type ordered alloy comprising Fe, Pt, and Ru, along with a nonmagnetic grain boundary material like carbon, boron, oxides, or nitrides, is developed, allowing for a granular structure that enhances magnetic isolation and reduces the Curie temperature while maintaining high anisotropy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the grain size of magnetic crystal grains is reduced to improve recording density, then recording density is improved, but thermal stability of written magnetization deteriorates
Solution Approach 1:
The patent changes the material composition parameter by introducing Ru into the L10-type ordered alloy, which fundamentally alters the temperature dependence characteristics of magnetic anisotropy constant Ku, enabling small grains to maintain high thermal stability
Solution Approach 2:
The patent creates a composite material system by combining Ru with L10-type ordered alloys (FePt, CoPt, FePd, or CoPd), forming a new alloy composition that exhibits both high magnetocrystalline anisotropy and reduced Curie temperature
2Reliability
If materials with higher magnetocrystalline anisotropies are used to compensate for reduced thermal stability, then thermal stability is improved, but coercivity increases making writing more difficult
Solution Approach 1:
The patent changes the temperature parameter during writing to resolve the contradiction. By temporarily increasing temperature, the magnetic anisotropy constant Ku decreases, reducing coercivity and enabling easy writing. After writing, cooling restores high Ku for thermal stability
Solution Approach 2:
The patent introduces dynamic temperature control during the writing process. The temperature is dynamically adjusted: increased during writing to reduce coercivity, then decreased after writing to restore thermal stability, creating a time-dependent solution to the static contradiction
3Temperature
If the Curie temperature Tc is lowered to enable writing at lower heating temperatures, then writing temperature is reduced, but magnetic anisotropy constant Ku at given temperature decreases
Solution Approach 1:
The patent changes the material composition parameter by adding Ru to the L10-type ordered alloy, which fundamentally alters the temperature dependence characteristics of magnetic anisotropy constant Ku. This enables the material to maintain high Ku values even at lower Curie temperatures, resolving the contradiction between writing temperature and magnetic anisotropy
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 enables writing at lower heating temperatures while ensuring high thermal stability of the written signal, with the Ru-containing ordered alloy maintaining a large anisotropic magnetic field and saturation magnetization.
Implementation Method 1
L10-type ordered alloys have been proposed as materials that have the required high magnetocrystalline anisotropies
Implementation Method 2
the ordered alloy contains at least one element selected from the group consisting of Fe and Ni, at least one element selected from the group consisting of Pt, Pd, Au, Rh and Ir, and Ru
Implementation Method 3
Thermally-assisted recording methods utilize the temperature dependence of the magnetic anisotropy constant (Ku) of magnetic materials, i.e., the characteristic that Ku declines as the temperature increases
Implementation Method 4
These methods use a head that has a heating function for the magnetic recording layer. Thus, by temporarily lowering Ku by raising the temperature of the magnetic recording layer, the reversal magnetic field can be lowered and writing can be carried out at this point
Implementation Method 5
The nonmagnetic grain boundary of the granular structure preferably contains at least one material selected from the group consisting of carbon, boron, oxides, carbides, and nitrides
Implementation Method 6
These methods use a head that has a heating function for the magnetic recording layer
Implementation Method 7
by temporarily lowering Ku by raising the temperature of the magnetic recording layer
Data Source
AI summary
The present invention provides a magnetic recording layer that has a high magnetic anisotropy constant Ku and a low Curie temperature Tc, as well as a magnetic recording medium that incorporates such a magnetic recording layer. The magnetic recording medium of the present invention includes a nonmagnetic substrate and a magnetic recording layer containing an ordered alloy. The ordered alloy may contain at least one element selected from the group consisting of Fe and Ni; at least one element selected from the group consisting of Pt, Pd, Au, Rh and Ir; and Ru.