NiFeX Alloy Free Layer for Magnetic Sensor Magnetostriction Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current magnetic detecting elements face challenges in maintaining large ΔRA (magnetoresistance variation) while reducing magnetostriction, particularly when using NiFe alloys, as increased ΔRA leads to higher magnetostriction, causing film distortion and sensitivity issues due to thermal expansion coefficient differences.
Innovation Solution
Incorporating an NiFeX alloy layer with elements like Cu, Sc, Ti, Zn, Zr, Hf, Au, Ag, Mn, and Al, with an average composition ratio of 5 to 20 atomic percent, and ensuring uniform diffusion to reduce magnetostriction while maintaining large ΔRA, and using diffusion preventive layers to prevent NiFeX alloy diffusion into non-magnetic layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the composition ratio of Ni in the NiFe alloy is adjusted to increase the value of ΔRA, then the magnetostriction becomes large, causing film distortion and sensitivity degradation
Solution Approach 1:
The invention changes the chemical composition parameters of the alloy by introducing a third element X (where X is at least one element selected from Cu, Sc, Ti, Zn, Zr, Hf, Au, Ag, Mn, and Al) into the NiFe alloy system. This compositional modification allows the material to achieve both large ΔRA and reduced magnetostriction simultaneously, resolving the trade-off between these two critical parameters
Solution Approach 2:
The invention creates a composite alloy system NiFeX by combining NiFe base alloy with additional element X. This composite material approach enables the free magnetic layer to exhibit optimized magnetic properties including large magnetoresistance variation and reduced magnetostriction, overcoming the limitations of binary NiFe alloys
2Strength
If the free magnetic layer is formed of CoFe alloy to increase uniaxial anisotropy and coercive force, then the sensitivity decreases due to difficulty in inverting magnetization with external magnetic field
Solution Approach 1:
The invention modifies the alloy composition parameters by using NiFeX instead of CoFe, adjusting the magnetic properties to achieve an optimal balance between coercive force and sensitivity. The specific composition range of element X (5 to 20 atomic percent) is carefully controlled to ensure the free magnetic layer can be easily inverted by external magnetic fields while maintaining sufficient coercive force
3Object-generated harmful factors
If a copper layer is included in the free magnetic layer to reduce magnetostriction, then the CoFe alloy below the copper layer oxidizes, causing demagnetization and deterioration of magnetic characteristics
Solution Approach 1:
The invention introduces element X as an intermediary element within the NiFeX alloy structure that performs the magnetostriction-reducing function without creating oxidation problems. This intermediary element protects the magnetic layers from oxidation while achieving the desired reduction in magnetostriction, eliminating the need for separate copper layers that cause demagnetization
Solution Approach 2:
The invention replicates the beneficial effect of copper layers (magnetostriction reduction) using element X within the NiFeX alloy system, but without the harmful side effects (oxidation). This functional copying allows the system to achieve magnetostriction control while maintaining magnetic layer stability and preventing demagnetization
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 effectively reduces magnetostriction while maintaining a high ΔRA value, enhancing the sensitivity and stability of magnetic detecting elements, particularly in CPP-type devices, by adjusting the composition and thickness ratios of the NiFeX alloy layers.
Implementation Method 1
the magnetostriction becomes large. The large magnetostriction causes problems in which a film is distorted
Implementation Method 2
using diffusion preventive layers to prevent NiFeX alloy diffusion into non-magnetic layers
Implementation Method 3
a magnetic detecting element including a pinned magnetic layer whose magnetization direction is fixed and a free magnetic layer which is formed on the pinned magnetic layer with a non-magnetic layer interposed therebetween and whose magnetization direction varies in accordance with an external magnetic field
Data Source
AI summary
There are provided a magnetic detecting element capable of maintaining large ΔRA and of reducing magnetostriction by improving a material forming a free magnetic layer, and a method of manufacturing the same. An NiFeX alloy layer is formed in a free magnetic layer. For example, the element X is Cu. The NiFeX alloy layer formed in the free magnetic layer makes it possible to maintain large ΔRA and to more reduce the magnetostriction of the free magnetic layer, compared with a structure in which an NiFe alloy layer is formed in the free magnetic layer.