CoMnXZ Alloy Free Layer for GMR Spin Valve Magnetostriction Reduction
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Solution Overview
Problem
Magnetic detecting elements with Heusler alloys exhibit improved ΔRA, but this is accompanied by increased magnetostriction, leading to stress-related noise and operational issues due to layer distortion and thermal expansion differences.
Innovation Solution
A magnetic detecting element with a CoMnXZ alloy layer, where the composition ratio of element Z is modulated from bottom to top, and a laminated structure with diffusion suppressing layers, reduces magnetostriction while maintaining a large ΔRA, by using a CoMnX alloy layer and an intermediate layer of Al, Sn, or Cr, and optimizing their thickness ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Heusler alloy is used for the free magnetic layer, then the product ΔRA of magnetic resistance change and element area is improved, but the magnetostriction of the free magnetic layer increases
Solution Approach 1:
The invention changes the chemical composition parameters of the free magnetic layer by introducing a specific alloy formula CoFe1-xMnxSi1-y (where 0 < x ≤ 0.5 and 0 < y ≤ 0.5) and controlling the stoichiometric ratios of elements. This parameter optimization allows achieving both large ΔRA and reduced magnetostriction simultaneously
Solution Approach 2:
The invention uses a composite alloy system combining Co, Fe, Mn, and Si elements in specific proportions. This composite material approach leverages the beneficial properties of each element: Co provides high spin polarization, Fe enhances magnetization, Mn increases magnetic moment, and Si reduces magnetostriction while maintaining electrical properties
2Reliability
If the magnetostriction of the free magnetic layer is reduced, then stress-related noise and operational issues are reduced, but the product ΔRA may decrease
Solution Approach 1:
The invention optimizes the composition parameters within specific ranges (0 < x ≤ 0.5, 0 < y ≤ 0.5) to achieve the optimal balance between magnetostriction reduction and ΔRA maintenance. The double-parameter control system allows fine-tuning of material properties
Solution Approach 2:
The invention introduces different elements at specific positions in the alloy structure to achieve local property optimization. Si elements are strategically incorporated to reduce magnetostriction in specific regions while maintaining overall magnetic performance
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 solution effectively reduces magnetostriction while preserving a large ΔRA, enhancing the operational stability and noise resistance of the magnetic detecting element.
Implementation Method 1
the magnetostriction of the free magnetic layer increases. When the magnetostriction of the free magnetic layer is large, influence of stress due to layer formation distortion or a difference between thermal expansion coefficients increases or noise is generated
Implementation Method 2
a magnetic detecting element including a pinned magnetic layer having a pinned magnetization direction and a free magnetic layer formed on the pinned magnetic layer having a non-magnetic material layer disposed between and of which the magnetization direction is changed by an external magnetic field
Data Source
AI summary
A magnetic detecting element capable of maintaining a large ΔRA and reducing magnetostriction by changing a material of a free magnetic layer, and a method of manufacturing the same is provided. A CoMnXZ alloy layer or CoMnXRh alloy layer is formed in a free magnetic layer where an element X is at least one or two elements of Ge, Ga, In, Si, Pb, and Zn, and an element X in the latter case is at least one or two elements of Ge, Ga, In, Si, Pb, Zn, Sn, Al, and Sb. By forming the CoMnXZ alloy layer or the CoMnXRh alloy layer in the free magnetic layer, the magnetostriction of the free magnetic layer can be reduced while maintaining the large ΔRA, compared with a case where only the CoMnX alloy is formed.