Ferrimagnetic Heusler Tunnel Junctions with Segmented Layers

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Solution Overview

Problem

Magnetic tunnel junctions using Heusler compounds exhibit low tunneling magnetoresistance (TMR) due to compensation from termination layers with opposite tunneling spin polarizations, despite having high perpendicular magnetic anisotropy, which limits their potential in magnetic random access memory applications.

Innovation Solution

A layered stack with two Heusler layers having the same tunneling spin polarization orientation but opposite magnetic moment orientations is used, allowing for the engineering of tunneling spin polarization to enhance TMR in magnetic tunnel junctions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If ferrimagnetic Heusler compounds are used in magnetic tunnel junctions, then perpendicular magnetic anisotropy is improved, but tunneling magnetoresistance deteriorates due to compensation from termination layers

Engineering Contradiction:

Improveperpendicular magnetic anisotropyVSAvoidtunneling magnetoresistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The magnetic electrode is segmented into multiple layers with different magnetic moment orientations. By dividing the electrode into layers with alternating magnetic moments, the patent achieves both high perpendicular magnetic anisotropy and high tunneling magnetoresistance, resolving the contradiction between these two properties in ferrimagnetic Heusler compounds

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the magnetic electrode are given different local properties through varying magnetic moment orientations in adjacent layers. This local differentiation allows the topological termination layer to have optimized spin polarization while maintaining overall perpendicular magnetic anisotropy, thereby achieving high TMR without sacrificing magnetic strength

Inventive Principle:

Principle #3Local quality

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 approach enables the development of magnetic random access memory with high TMR, overcoming the limitations of ferrimagnetic Heusler compounds by aligning tunneling spin polarization with magnetic moment orientations, potentially improving memory device performance.

Implementation Method 1

there has been no experimental observation to date of high tunneling magnetoresistance (TMR) in the latter

Methodology Applied

Scientific EffectTunneling magnetoresistance: Magnetoresistance

Implementation Method 2

A preferred embodiment of the invention is a layered stack that includes a first layer having a first tunneling spin polarization and a first magnetic moment, and a second layer having a second tunneling spin polarization and a second magnetic moment

Methodology Applied

Scientific EffectSpin polarization:

Data Source

PatentUS9666215B2Termination layer-compensated tunneling magnetoresistance in ferrimagnetic Heusler compounds with high perpendicular magnetic anisotropy

Publication Date: 2017.05.30 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

A layered stack includes a first layer having a first spin polarization and a first magnetic moment, as well as a second layer (in contact with the first layer) having a second spin polarization a second magnetic moment. The first and second spin polarizations have the same orientation, but the first and second magnetic moments have orientations that partially cancel each other, thereby recommending the layered stack for applications in magnetic tunnel junctions, for example.