CoMnα Alloy Free Magnetic Layer for High ΔRA and Low Hin
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Solution Overview
Problem
The existing current-perpendicular-to-plane-mode (CPP-mode) magnetic sensing elements with a free magnetic layer composed of Co2MnGe face challenges in achieving a high product of magnetoresistance rate change (ΔRA) and low interlayer coupling magnetic field (Hin), which affects recording density and stability, due to increased coercive force and magnetostriction.
Innovation Solution
Incorporating a CoMnα alloy sublayer with specific atomic compositions, such as Co2xMnxαy, where α contains elements like Ge, Ga, In, Si, Pb, Zn, Sn, or Al, and y ranges from 24 to 28 atomic percent, between the pinned and free magnetic layers, along with a laminated structure, to reduce interlayer coupling magnetic field and coercive force, thereby enhancing stability and ΔRA.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the free magnetic layer is composed of Co2MnGe, then the product ΔRA increases, but the interlayer coupling magnetic field Hin increases disadvantageously
Solution Approach 1:
The patent changes the chemical composition parameters of the free magnetic layer by incorporating multiple alloying elements (Ga, In, Si, Pb, Zn, Sn, Al) in specific concentrations. By adjusting these compositional parameters, the patent achieves a balance where ΔRA remains high while Hin is suppressed compared to conventional Co2MnGe alloys
Solution Approach 2:
The patent creates a composite magnetic alloy system by combining Co, Mn, and multiple other elements (Ga, In, Si, Pb, Zn, Sn, Al) in a multi-element alloy structure. This composite material approach allows simultaneous optimization of magnetoresistance properties and reduction of interlayer coupling effects
2Measurement precision
If the free magnetic layer is composed of Co2MnGe, then the product ΔRA increases, but the coercive force increases
Solution Approach 1:
The patent modifies the compositional parameters of the free magnetic layer by incorporating multiple elements in optimized ratios. This parameter optimization reduces coercive force while maintaining high ΔRA, addressing the contradiction between measurement precision and magnetic switching ease
3Measurement precision
If the free magnetic layer is composed of Co2MnGe, then the product ΔRA increases, but the magnetostriction increases
Solution Approach 1:
The patent changes the compositional parameters by incorporating multiple alloying elements in specific concentrations that reduce magnetostriction. This allows maintaining high ΔRA while improving compositional stability by minimizing magnetostrictive effects
4Measurement precision
If the free magnetic layer is composed of Co2MnGe, then the product ΔRA increases, but the read characteristics stability decreases
Solution Approach 1:
The patent optimizes compositional parameters by incorporating multiple elements in balanced ratios, which simultaneously achieves high ΔRA and improved read characteristics stability through reduced coercive force and magnetostriction
Solution Approach 2:
The multi-element composite alloy structure provides a more stable magnetic system with balanced properties, achieving both high magnetoresistance rate change and improved read characteristics stability compared to conventional Co2MnGe
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 achieves a high ΔRA and low interlayer coupling magnetic field, improving the stability of read characteristics and reducing asymmetry, while maintaining a low coercive force and magnetostriction, outperforming conventional CoMnGe-based structures.
Implementation Method 1
an interlayer coupling magnetic field Hin acting between the pinned magnetic layer and the free magnetic layer increased
Implementation Method 2
The free magnetic layer composed of Co2MnGe has relatively high coercive force and magnetostriction. Thus, to improve the stability of the read characteristics, preferably, these magnetic properties are also minimized.
Implementation Method 3
The free magnetic layer composed of Co2MnGe has relatively high coercive force and magnetostriction. Thus, to improve the stability of the read characteristics, preferably, these magnetic properties are also minimized.
Implementation Method 4
a current-perpendicular-to-plane-mode magnetic sensing element (CPP-mode magnetic sensing element) including a free magnetic layer composed of a Heusler alloy such as Co2MnGe
Data Source
AI summary
A magnetic sensing element is provided. A free magnetic layer has a three-layer structure including CoMnα sublayers each composed of a metal compound represented by the formula: Co2xMnxαy. The α contains an element β and Sb, the element β being at least one element selected from Ge, Ga, In, Si, Pb, Zn, Sn, and Al. The concentration x and the concentration y are each represented in terms of atomic percent and satisfy the equation: 3x+y=100 atomic percent. One of the CoMnα sublayers is in contact with a lower nonmagnetic material layer. The other CoMnα sublayer is in contact with upper nonmagnetic material layer. As a result, it is possible to achieve a high ΔRA and a lower interlayer coupling magnetic field Hin compared with the known art.