Magnetostrictive Layer System with Optimized Exchange Bias
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Solution Overview
Problem
Current magnetostrictive layers with self-bias generate non-zero net magnetization, causing stray fields and hindering miniaturization and sensitivity in magnetoelectric sensors, especially when detecting small magnetic fields.
Innovation Solution
A layer system comprising an antiferromagnetic layer and a ferromagnetic layer with an exchange bias field, where the ferromagnetic layer has an exchange bias-induced magnetization greater than 85% in the zero field, and the angle between the exchange bias field direction and the magnetostriction direction is optimized between 10° and 80° to maximize the piezomagnetic coefficient in the zero field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetostrictive layer with self-bias is used to generate a supporting field, then the sensor can detect small magnetic fields, but non-zero net magnetization causes stray fields that increase device complexity and hinder miniaturization
Solution Approach 1:
The patent changes the magnetization parameter by optimizing the exchange bias field strength and angle, achieving a state where the magnetostrictive layer has high piezomagnetic coefficient but minimal net magnetization. This parameter optimization allows the layer to provide supporting field functionality without generating problematic stray fields
Solution Approach 2:
The patent uses a composite structure combining antiferromagnetic and magnetostrictive layers. The antiferromagnetic layer provides exchange bias to the magnetostrictive layer, creating a composite system that generates minimal stray fields while maintaining high detection sensitivity through optimized magnetization alignment
2Measurement precision
If the exchange bias field strength is increased to maximize piezomagnetic coefficient, then sensitivity improves, but net magnetization increases causing stronger stray fields
Solution Approach 1:
The patent optimizes two parameters simultaneously: exchange bias field strength and exchange bias angle. By adjusting both parameters, the system achieves maximum piezomagnetic coefficient while minimizing net magnetization and resulting stray fields
Solution Approach 2:
The patent creates different magnetic properties in different regions of the magnetostrictive layer by optimizing the exchange bias orientation. The layer exhibits high piezomagnetic response in the measurement direction while maintaining low net magnetization overall, achieving local optimization of magnetic properties
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 piezomagnetic coefficient in the zero field with minimal stray fields, enabling highly sensitive magnetoelectric sensors with intrinsic supporting fields, suitable for detecting small magnetic fields without the noise and complexity of permanent magnets.
Implementation Method 1
Magnetostriction of a material refers to its change in shape and/or volume under the influence of an external magnetic field
Implementation Method 2
A layer system comprising at least one antiferromagnetic (AFM) layer and a magnetostrictive, ferromagnetic (FM) layer arranged immediately thereon and having an exchange bias (EB) field
Implementation Method 3
very suitable for transferring the change in length of the magnetostrictive material to the piezoelectric material by means of the mechanical coupling and causing a change in the electrical polarization state there
Data Source
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AI summary
A magnetostrictive layer system is proposed comprising at least one layer sequence of ■ an antiferromagnetic (AFM) layer and ■ a magnetostrictive, ferromagnetic (FM) layer arranged directly thereon, wherein the layer sequence has an associated exchange bias (EB) field, characterized in that □ the EB-induced degree of magnetization of the FM layer in the absence of an external magnetic field lies in a range between 85% and 100% and □ the angle αopt enclosed by the EB field direction and the magnetostriction direction, which has the maximum piezomagnetic coefficient in the absence of an external magnetic field, within a plane parallel to the (AFM) layer and the (FM) layer, lies in a range between 10° and 80°.