Magnetic Detecting Element Free Layer Magnetostriction Reduction
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Solution Overview
Problem
Existing magnetic detecting elements with Heusler alloys in the fixed magnetic layer fail to improve soft magnetic properties effectively due to high magnetostriction constants, which affect detection sensitivity and stability.
Innovation Solution
A magnetic detecting element with a multilayer film structure featuring a Co2MnZ alloy layer and a CoaFe100-a alloy layer, where the CoaFe100-a alloy layer has a face-centered cubic structure and is in contact with a nonmagnetic material layer, reducing the magnetostriction constant and improving soft magnetic properties by setting the composition ratio and film thickness within specific ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Heusler alloy is used in the fixed magnetic layer, then the magnetization can be properly fixed in the height direction, but the soft magnetic properties cannot be improved satisfactorily due to high magnetostriction constant
Solution Approach 1:
The free magnetic layer is divided into two distinct layers: a Co2MnZ alloy layer (Heusler alloy) and a CoaFe100-a alloy layer. The Co2MnZ layer provides magnetization fixation through exchange coupling with the antiferromagnetic layer, while the CoaFe100-a layer contributes to reducing the overall magnetostriction constant and improving soft magnetic properties. This segmentation allows each layer to fulfill its specific function independently.
Solution Approach 2:
The invention uses a composite structure combining Co2MnZ alloy (Heusler alloy with high spin polarization) and CoaFe100-a alloy (with low magnetostriction constant) in the free magnetic layer. This composite material approach leverages the advantageous properties of both materials: the Co2MnZ layer provides strong magnetic anisotropy and exchange coupling, while the CoaFe100-a layer reduces magnetostriction and improves soft magnetic characteristics.
2Object-affected harmful factors
If the magnetostriction constant is decreased to improve soft magnetic properties, then detection sensitivity improves, but the structural stability may be affected
Solution Approach 1:
The invention optimizes specific parameters including the composition ratio (76≦a≦100 for CoaFe100-a alloy), film thickness (10 to 30 nm for CoaFe100-a layer, 30 to 80 nm for Co2MnZ layer), and crystal structure (face-centered cubic with {111} plane orientation). These parameter changes enable the CoaFe100-a layer to contribute negatively to magnetostriction while maintaining structural stability through proper thickness and crystallographic orientation.
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 the magnetostriction constant and coercive force of the free magnetic layer, enhancing soft magnetic properties and detection sensitivity while minimizing noise from spin transfer torque, making the magnetic detecting element suitable for practical use.
Implementation Method 1
the CoaFe100-a alloy layer has a face-centered cubic structure and is in contact with a nonmagnetic material layer, reducing the magnetostriction constant
Implementation Method 2
minimizing noise from spin transfer torque
Implementation Method 3
An exchange-coupling magnetic field is generated at the interface between the antiferromagnetic layer 3 and the fixed magnetic layer 4, and the magnetization of the fixed magnetic layer 4 is fixed in a height direction
Data Source
AI summary
A free magnetic layer is a laminated body of a Co2MnZ alloy layer (Z is one or more elements selected from a group consisting of Al, Sn, In, Sb, Ga, Si, Ge, Pb, and Zn) and a CoaFe100-a alloy layer. The CoaFe100-a alloy layer has a composition ratio 76≦a≦100 or a face-centered cubic (fcc) structure, in which an equivalent crystal face expressed as a {111} plane is preferentially oriented in a direction parallel to a film surface, and the CoaFe100-a alloy layer is in contact with the nonmagnetic material layer.