Heusler Alloy MR Element Heat Reliability
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Solution Overview
Problem
Conventional magneto-resistance elements, such as CPP-GMR elements, face limitations in achieving high magnetic resistance change rates and heat reliability due to low spin polarizability of materials like Fe and Co, and the Curie temperature issues with full-Heusler alloys made from precious metals.
Innovation Solution
Incorporating a Heusler alloy with a composition formula X2YZ, where X is a precious metal, Y is a transition metal from the Mn, V, or Ti group, and Z is an element from group III to group V, and replacing a part of the composition with Co, to create a full-Heusler alloy for both the pinned and free layers, optimizing the atomic composition ratio of Co between 0.5 and 0.85, which enhances the magnetic resistance change rate and Curie temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional spin valve GMR elements are used with Fe and Co materials, then the structure is simple and manufacturing is easier, but the spin polarizability is low resulting in insufficient magnetic resistance change rate
Solution Approach 1:
The patent employs full-Heusler alloy composite materials with specific composition formula X2YZ where X is a precious metal (Pd, Pt, Rh, Ir), Y is a transition metal (Mn, V, Ti), and Z is a main group element (Al, Si, Ga, Ge, Sn). This composite material approach achieves high spin polarizability (theoretical value of 1) and high Curie temperature, resolving the contradiction between magnetic resistance change rate and material complexity by selecting optimized composite materials rather than conventional simple ferromagnetic materials.
Solution Approach 2:
The patent systematically varies the atomic composition ratio of Co in the Heusler alloy (optimizing at 0.5 to 0.85) and adjusts film thickness parameters (pinned layer 2-10 nm, free layer 2-10 nm, spacer layer 1-5 nm) to achieve optimal magnetic resistance change rate. This parameter optimization approach enables achieving high performance while controlling material complexity.
2Reliability
If full-Heusler alloys made from precious metals are used, then the magnetic resistance change rate and Curie temperature are improved, but the heat radiation efficiency deteriorates due to low thermal conductivity of precious metals
Solution Approach 1:
The patent creates a composite material system where precious metal elements (Pd, Pt, Rh, Ir) are combined with transition metals (Mn, V, Ti) and main group elements (Al, Si, Ga, Ge, Sn) in the Heusler alloy structure. This composite approach achieves high Curie temperature (improving heat reliability) while the specific composition optimization balances thermal conductivity properties, resolving the contradiction between heat reliability and heat radiation efficiency.
Solution Approach 2:
The patent optimizes the atomic composition ratio of Co (0.5 to 0.85) and adjusts the stoichiometry of the Heusler alloy to achieve the desired balance between Curie temperature and thermal conductivity. By precisely controlling compositional parameters, the patent achieves high heat reliability through elevated Curie temperature while maintaining adequate heat radiation efficiency.
3Productivity
If the element area is reduced to achieve higher recording density, then the track width is narrowed and recording capacity increases, but the heat radiation efficiency is lowered and operating current reliability is restricted
Solution Approach 1:
The patent optimizes the film thickness parameters (pinned layer 2-10 nm, free layer 2-10 nm, spacer layer 1-5 nm) to achieve high magnetic resistance change rate in miniaturized elements. This parameter optimization enables narrow track width (high recording density) while maintaining adequate operating current reliability through enhanced spin polarizability and magnetic resistance characteristics.
Solution Approach 2:
The use of full-Heusler alloy composite materials with high spin polarizability compensates for the reduced heat radiation efficiency in miniaturized elements. The high spin polarizability (theoretical value of 1) enhances the magnetic resistance change rate, which improves signal strength and enables reliable operation even in elements with reduced area and narrowed track width.
4Reliability
If conventional materials with low spin polarizability are used, then the manufacturing process is simpler and costs are lower, but the magnetic resistance change rate is insufficient for practical use
Solution Approach 1:
The patent optimizes deposition parameters including film thickness (pinned layer 2-10 nm, free layer 2-10 nm, spacer layer 1-5 nm) and atomic composition ratios (Co ratio 0.5 to 0.85) to achieve high magnetic resistance change rate. These parameter optimizations enable practical use performance while maintaining compatibility with existing sputtering and deposition technologies, balancing manufacturing ease with performance requirements.
Solution Approach 2:
The patent employs full-Heusler alloy composite materials that can be deposited using conventional sputtering techniques. The specific composition formula X2YZ with precious metals (Pd, Pt, Rh, Ir), transition metals (Mn, V, Ti), and main group elements (Al, Si, Ga, Ge, Sn) achieves high spin polarizability and magnetic resistance change rate while remaining compatible with standard thin-film deposition processes, resolving the contradiction between performance and manufacturing ease.
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 results in a higher magnetic resistance change rate and improved heat radiation efficiency, achieving high heat reliability and enhanced performance in thin film magnetic heads with narrower tracks.
Implementation Method 1
The magnetization direction of second ferromagnetic film 130 is vertical to the magnetization direction of first ferromagnetic film 126 when the externally-applied magnetic field is zero... the resistance value becomes larger as the cross-sectional area of the element becomes smaller, and the resistance change amount is increased
Implementation Method 2
The magnetization direction of first ferromagnetic film 126 is fixed by making antiferromagnetic film 124 adjacent thereto and by applying unidirectional anisotropy energy (also called 'exchange bias' or 'coupling magnetic field') to first ferromagnetic film 126 by exchange coupling between antiferromagnetic film 124 and first ferromagnetic film 126
Implementation Method 3
a magneto-resistance element that is operated by feeding a current in parallel with a film surface, which is called a spin-valve-type Giant Magnetoresistance (GMR) element
Data Source
AI summary
A magneto-resistance element according to the present invention has a pinned layer whose magnetization direction is fixed; a free layer whose magnetization direction varies in accordance with an external magnetic field; and a nonmagnetic spacer layer that is arranged between the pinned layer and the free layer, at least the pinned layer or the free layer includes a layer having Heusler alloy represented by composition formula X2YZ (where X is a precious metal element, Y is a transition metal of Mn, V, or Ti group, Z is an element from group III to group V), and a part of composition X is replaced with Co, and an atomic composition ratio of Co in composition X is from 0.5 to 0.85.