Magnetoresistance Recording Layer Structure for Faster Domain Wall Motion

Solution Overview

Problem

Magnetic domain wall moving elements in magnetoresistance effect devices experience slow moving speeds due to high saturation magnetization in the magnetic recording layer, leading to gradual resistance value changes and analog data recording, which is undesirable. Additionally, the leakage magnetic field from these elements affects neighboring components.

Innovation Solution

The magnetoresistance effect element is designed with a magnetic recording layer comprising a first and second ferromagnetic layer, a spacer layer, and a magnetization reference layer. The first ferromagnetic layer has a central region with a higher product of film thickness and saturation magnetization compared to the outer region, where the second ferromagnetic layer projects outward. This configuration reduces the leakage magnetic field.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the saturation magnetization of the magnetic recording layer is increased, then the data retention capability is improved, but the moving speed of the magnetic domain wall slows down and the leakage magnetic field increases

Engineering Contradiction:

Improvedata retention capabilityVSAvoidmoving speed of magnetic domain wall

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The magnetic recording layer is divided into a central region with higher saturation magnetization (for data retention) and an outer region with lower saturation magnetization (for faster domain wall movement and reduced leakage field). This spatial differentiation of magnetic properties resolves the contradiction between data retention and domain wall mobility.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The magnetic recording layer is segmented into multiple ferromagnetic layers with different saturation magnetization characteristics. The first ferromagnetic layer has higher saturation magnetization in the central region, while the second ferromagnetic layer has lower saturation magnetization in the outer region, allowing simultaneous optimization of data retention and domain wall speed.

Inventive Principle:

Principle #1Segmentation

2Reliability

If the saturation magnetization of the magnetic recording layer is increased, then the data retention capability is improved, but the leakage magnetic field increases affecting other elements

Engineering Contradiction:

Improvedata retention capabilityVSAvoidleakage magnetic field

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The magnetic recording layer is divided into a central region with higher saturation magnetization (for data retention) and an outer region with lower saturation magnetization (for reduced leakage field). This spatial differentiation of magnetic properties resolves the contradiction between data retention and domain wall mobility.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The outer region with lower saturation magnetization converts the harmful leakage magnetic field into a beneficial feature by reducing the overall magnetic field leakage while maintaining the central region's high retention capability. The lower magnetization outer region acts as a magnetic field buffer.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Speed

If the saturation magnetization of the magnetic recording layer is decreased, then the moving speed of the magnetic domain wall increases, but the data retention capability deteriorates

Engineering Contradiction:

Improvemoving speed of magnetic domain wallVSAvoiddata retention capability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The magnetic recording layer is divided into a central region with higher saturation magnetization (for data retention) and an outer region with lower saturation magnetization (for faster domain wall movement and reduced leakage field). This spatial differentiation of magnetic properties resolves the contradiction between data retention and domain wall mobility.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The magnetic recording layer is segmented into multiple ferromagnetic layers with different saturation magnetization characteristics. The first ferromagnetic layer has higher saturation magnetization in the central region, while the second ferromagnetic layer has lower saturation magnetization in the outer region, allowing simultaneous optimization of data retention and domain wall speed.

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 configuration significantly reduces the leakage magnetic field, allowing for faster domain wall movement and improved data recording capabilities, including the ability to record multiple values or analog data. This design enhances the integration density of magnetic recording arrays by minimizing the distance between adjacent elements.

Implementation Method 1

The first ferromagnetic layer and the second ferromagnetic layer are antiferromagnetically coupled to each other

Methodology Applied

Scientific EffectAntiferromagnetic coupling: Magnetism

Implementation Method 2

The MRAM uses the change in the resistance value, which is caused by a change in the orientation of magnetization, for data recording

Methodology Applied

Scientific EffectMagnetoresistance effect: Magnetoresistance

Data Source

PatentUS12225830B2Magnetoresistance effect element and magnetic recording array

Publication Date: 2025.02.11 TDK CORP

AI summary

A magnetoresistance effect element includes a magnetic recording layer which includes a ferromagnetic material, a non-magnetic layer laminated on the magnetic recording layer, and a magnetization reference layer which is laminated on the non-magnetic layer. The magnetic recording layer includes a first ferromagnetic layer, a spacer layer, and a second ferromagnetic layer in order from the non-magnetic layer. The first ferromagnetic layer and the second ferromagnetic layer are antiferromagnetically coupled to each other. The magnetic recording layer has a central region in which a product of a film thickness and saturation magnetization of the first ferromagnetic layer is greater than a product of a film thickness and saturation magnetization of the second ferromagnetic layer, and an outer region in which the product of the film thickness and the saturation magnetization of the first ferromagnetic layer is smaller than the product of the film thickness and the saturation magnetization of the second ferromagnetic layer.