Heusler Alloy Magnetoresistance Element Crystallization

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Solution Overview

Problem

The existing magnetoresistance effect elements with Heusler alloy ferromagnetic layers face challenges in achieving a large magnetoresistance change rate (MR ratio) due to the amorphous nature of the ferromagnetic layers, which limits their output performance.

Innovation Solution

A magnetoresistance effect element is designed with a structure comprising a first and second ferromagnetic layer, a first and second non-magnetic layer, where the ferromagnetic layers include Heusler alloy layers that are crystallized, and the second non-magnetic layer is a (001)-oriented oxide containing Mg with a discontinuous portion, optimizing the area ratio and composition to enhance the MR ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If Heusler alloy ferromagnetic layers are used to increase spin polarization and output signal, then the output performance is improved, but the ferromagnetic layers remain amorphous and the MR ratio is insufficient

Engineering Contradiction:

Improveoutput signalVSAvoidMR ratio

Core Design Contradiction:

PowerVSManufacturing precision

Solution Approach 1:

The patent changes the crystalline state parameter of the Heusler alloy ferromagnetic layers from amorphous to crystalline by controlling the substrate temperature during film formation. The substrate is heated to 100°C to 550°C to enable crystallization of the Heusler alloy layers, which directly improves the MR ratio while maintaining the spin polarization benefits.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces a new dimension of crystallinity control by using a heated substrate during film deposition. This thermal dimension enables the Heusler alloy layers to crystallize in-situ during the sputtering process, resolving the contradiction between maintaining amorphous structure and achieving high MR ratio.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If the substrate temperature is increased to enable Heusler alloy crystallization, then the MR ratio is improved, but the film formation becomes more difficult and requires thick underlying substrates

Engineering Contradiction:

ImproveMR ratioVSAvoidfilm formation process

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent applies preliminary heating to the substrate before and during film formation. By pre-heating the substrate to the appropriate temperature range (100°C to 550°C), the Heusler alloy layers crystallize during deposition without requiring post-deposition annealing or thick underlying substrates, simplifying the overall manufacturing process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The heated substrate acts as an intermediary that facilitates crystallization during film formation. The substrate temperature serves as a mediating parameter that enables controlled crystallization of the Heusler alloy layers without requiring complex post-processing steps or thick underlying substrates.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If a discontinuous non-magnetic layer is introduced to optimize the structure, then the MR ratio is significantly improved, but the device structure becomes more complex

Engineering Contradiction:

ImproveMR ratioVSAvoidlayer structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent segments the non-magnetic layer into two distinct parts: a first non-magnetic layer and a second non-magnetic layer with discontinuous portions. This segmentation allows the second non-magnetic layer to be positioned strategically to enhance spin-dependent scattering while maintaining structural simplicity through standard sputtering deposition.

Inventive Principle:

Principle #1Segmentation

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 proposed structure achieves a significant increase in the MR ratio, allowing for improved output performance and accurate data recording in applications such as magnetic sensors and memory devices.

Implementation Method 1

A magnetoresistance effect element is an element that changes a resistance value in a lamination direction by a magnetoresistance effect

Methodology Applied

Scientific EffectMagnetoresistance effect: Magnetoresistance

Implementation Method 2

The Heusler alloy has high spin polarization and is expected to increase an output signal of the magnetic sensor

Methodology Applied

Scientific EffectSpin polarization:

Data Source

PatentUS11525873B2Magnetoresistance effect element including at least one Heusler alloy layer and at least one discontinuous non-magnetic layer

Publication Date: 2022.12.13 TDK CORP

AI summary

A magnetoresistance effect element includes a first ferromagnetic layer, a second ferromagnetic layer, a first non-magnetic layer; and a second non-magnetic layer, wherein, the first ferromagnetic layer and the second ferromagnetic layer are formed so that at least one of them includes a Heusler alloy layer, the first non-magnetic layer is provided between the first ferromagnetic layer and the second ferromagnetic layer, the second non-magnetic layer is in contact with any surface of the Heusler alloy layer and has a discontinuous portion with respect to a lamination surface, and the second non-magnetic layer is made of a material different from that of the first non-magnetic layer and is a (001)-oriented oxide containing Mg.