Magnetic Sensor S/N Improvement via Amorphous Metal Layer

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Solution Overview

Problem

Magnetic sensors using soft magnetic material layers often experience a reduction in signal-to-noise ratio (S/N) due to the formation of closure magnetic domains, which leads to noise from discontinuous magnetic domain wall displacement, known as the Barkhausen effect.

Innovation Solution

Incorporating a nonmagnetic amorphous metal layer, such as CrTi or AlTi, between soft magnetic material layers to prevent antiferromagnetic coupling and suppress the formation of closure magnetic domains, thereby improving the S/N ratio by reducing noise associated with the Barkhausen effect.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If soft magnetic material layers are used in the magnetic sensor, then the magnetic impedance effect is achieved, but the signal-to-noise ratio is reduced due to closure magnetic domain formation and Barkhausen effect

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidnoise from Barkhausen effect

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The soft magnetic material layer is divided into multiple thin layers (first soft magnetic material layer and second soft magnetic material layer) separated by a nonmagnetic amorphous metal layer. This segmentation prevents the formation of closure magnetic domains that cause Barkhausen effect noise, thereby improving the signal-to-noise ratio while maintaining magnetic impedance effect functionality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A nonmagnetic amorphous metal layer is introduced as an intermediary between the first and second soft magnetic material layers. This intermediate layer decouples the magnetic interaction between adjacent soft magnetic layers, preventing closure domain formation and reducing Barkhausen noise, thus enhancing reliability without sacrificing the magnetic sensing capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a nonmagnetic amorphous metal layer is introduced between soft magnetic material layers, then closure magnetic domains are suppressed and S/N ratio improves, but device structure becomes more complex

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs a composite structure combining soft magnetic material layers with a nonmagnetic amorphous metal layer. This composite design leverages the complementary properties of both materials: the soft magnetic material provides magnetic impedance effect while the nonmagnetic amorphous metal suppresses closure domains, achieving improved S/N ratio through material composition rather than complex geometric arrangements.

Inventive Principle:

Principle #40Composite materials

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 use of nonmagnetic amorphous metal layers between soft magnetic material layers in magnetic sensors enhances the signal-to-noise ratio by preventing the formation of closure magnetic domains, thus reducing noise and improving sensitivity.

Implementation Method 1

the soft magnetic material layers facing each other with the nonmagnetic amorphous metal layer interposed therebetween are antiferromagnetically coupled

Methodology Applied

Scientific EffectAntiferromagnetic coupling: Magnetism

Implementation Method 2

allow the sensitive element to sense a magnetic field by a magnetic impedance effect

Methodology Applied

Scientific EffectMagnetic impedance effect: Magnetism

Implementation Method 3

noise from discontinuous magnetic domain wall displacement, known as the Barkhausen effect

Methodology Applied

Scientific EffectBarkhausen effect: Barkhausen Effect

Data Source

PatentUS11561266B2Magnetic sensor

Publication Date: 2023.01.24 RESONAC CORP

AI summary

Reduction of the S/N in an output from a magnetic sensor using the magnetic impedance effect is suppressed. A magnetic sensor 1 is provided with a sensitive element 31 including: plural soft magnetic material layers 105; and a nonmagnetic amorphous metal layer 106 provided between the plural soft magnetic material layers 105, wherein the soft magnetic material layers 105 facing each other with the nonmagnetic amorphous metal layer 106 interposed therebetween are antiferromagnetically coupled to sense a magnetic field by a magnetic impedance effect.