Exchange Bias Magnetization Element for Stable Analog Memory

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Solution Overview

Problem

Conventional magnetic domain wall drive type MRAMs face challenges in maintaining data integrity due to magnetic domain wall movement during reading, erroneous writing or reading, and vulnerability to external magnetic fields, limiting their use as analog memory.

Innovation Solution

An exchange bias utilization type magnetization rotational element is developed, comprising an anti-ferromagnetic driving layer with a zinc-blende structure or materials like CuMnAs and Mn2Au, coupled with a magnetic coupling layer and electrode layers, which allows for stable magnetization control and resistance changes, enhancing environmental resistance to external magnetic fields.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a current is caused to flow in an in-plane direction of the magnetic domain wall driving layer at the time of reading, then reading operation can be performed, but magnetic domain wall may move and cause erroneous writing or reading

Engineering Contradiction:

Improvereading operationVSAvoiddata integrity

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The magnetic domain wall driving layer is divided into multiple regions (first region, second region, third region) with different magnetic domain configurations. This segmentation allows the reading current to flow through specific regions without causing unwanted domain wall movement that would affect data integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the magnetic domain wall driving layer are given different local magnetic properties. The first and second regions have magnetic domains oriented in different directions, creating localized quality differences that enable selective reading without triggering erroneous writing operations in other regions.

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If magnetic domain wall is used for recording information, then data storage is achieved, but external magnetic field may cause magnetic domain wall movement and information loss

Engineering Contradiction:

Improveinformation storageVSAvoidexternal magnetic field vulnerability

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The magnetic domain structure is designed with asymmetric properties where the magnetic domains in different regions are oriented in specific directions. This asymmetric configuration creates inherent stability against external magnetic fields, as the domains are locked in specific orientations that resist field-induced changes.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

Instead of using a uniform magnetic domain structure that is vulnerable to external fields, the invention inverts the approach by creating alternating magnetic domains in different regions. This inverted structure provides natural protection against external magnetic field interference while maintaining information storage capability.

Inventive Principle:

Principle #13The other way round (Inversion)

3Adaptability or versatility

If magnetic domain wall position is used for analog recording, then analog memory functionality is achieved, but magnetic domain wall movement during reading causes signal degradation

Engineering Contradiction:

Improveanalog memory functionalityVSAvoidsignal stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The invention transitions from using only the position of the magnetic domain wall along a single dimension to utilizing the magnetic domain configuration across multiple regions. By adding the dimension of spatial distribution across first, second, and third regions with different domain orientations, the system achieves analog recording capability while maintaining signal stability during reading operations.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 enables high environmental resistance to external magnetic fields and stable analog recording, preventing erroneous writing or reading and maintaining data integrity, thus enabling the use of MRAMs as both digital and analog memory devices.

Implementation Method 1

exchange bias utilization type magnetization rotational element

Methodology Applied

Scientific EffectExchange bias: Magnetism

Implementation Method 2

moving a magnetic domain wall using a spin transfer effect by spin-polarized electrons

Methodology Applied

Scientific EffectSpin transfer effect: Magnetism

Data Source

PatentUS10672446B2Exchange bias utilization type magnetization rotational element, exchange bias utilization type magnetoresistance effect element, exchange bias utilization type magnetic memory, non-volatile logic circuit, and magnetic neuron element

Publication Date: 2020.06.02 TDK CORP

AI summary

An exchange bias utilization type magnetization rotational element includes an anti-ferromagnetic driving layer which is made of first region and second region anti-ferromagnetisms, and a third region anti-ferromagnetism positioned between the first and second regions, a magnetic coupling layer anti-ferromagnetism which is magnetically coupled to the anti-ferromagnetic driving layer anti-ferromagnetism in the third region anti-ferromagnetism, a first electrode layer anti-ferromagnetism which is bonded to the first region anti-ferromagnetism; and a second electrode layer anti-ferromagnetism which is bonded to the second region anti-ferromagnetism.