Canted Antiferromagnetic Memory Interface for Stronger Readout

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Solution Overview

Problem

The readout signal from antiferromagnet-based magnetic memory elements is too weak to be of practical use.

Innovation Solution

A magnetic memory element is designed with a canted antiferromagnetic layer and a contact layer, where the interface roughness is 1.0 nm or less, allowing a spin current to induce torque for magnetic order reversal, enhancing the readout signal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a conventional interface between antiferromagnetic layer and contact layer is used, then the magnetic memory element can be fabricated, but the readout signal is too weak to be of practical use

Engineering Contradiction:

Improvereadout signal strengthVSAvoidreadout signal detectability

Core Design Contradiction:

Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent changes the physical parameter of interface roughness from conventional values to 1.0 nm or less, which fundamentally alters the spin current injection efficiency and enhances the readout signal strength to practical levels

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies a localized quality improvement at the interface between the antiferromagnetic layer and contact layer by achieving ultra-smooth interface (1.0 nm or less roughness), which locally enhances spin current injection and thereby improves the overall readout signal

Inventive Principle:

Principle #3Local quality

2Measurement precision

If interface roughness is reduced to 1.0 nm or less, then spin current injection is enhanced and readout signal is improved, but manufacturing precision requirements are significantly increased

Engineering Contradiction:

Improvereadout signal strengthVSAvoidinterface roughness control

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent identifies interface roughness as a critical parameter and sets it to 1.0 nm or less, which optimizes the balance between achieving sufficient spin current injection and maintaining manufacturability through controlled deposition processes

Inventive Principle:

Principle #35Parameter changes

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 smooth interface between the antiferromagnetic and contact layers increases the spin current injection, maintaining optimal magnetic characteristics and enhancing the readout signal.

Implementation Method 1

applying an electrical current in a multilayer film including a ferromagnet and a non-magnetic heavy metal (such as tungsten (W) and platinum (Pt)) causes the magnetization reversal phenomenon which is called spin-orbit torque magnetization reversal

Methodology Applied

Scientific EffectSpin-orbit torque:

Implementation Method 2

increase a spin current to be injected from the contact layer into the antiferromagnetic layer via the interface

Methodology Applied

Scientific EffectSpin current injection:

Data Source

PatentUS12633329B2Magnetic memory element

Publication Date: 2026.05.19 THE UNIV OF TOKYO

AI summary

A magnetic memory element includes an antiferromagnetic layer made of a canted antiferromagnet having a magnetic order with a canted magnetic moment, and a contact layer in contact with the antiferromagnetic layer and made of a different material from the canted antiferromagnet. A roughness of an interface between the antiferromagnetic layer and the contact layer is 1.0 nm or less. A spin current flowing through the contact layer is configured to induce a torque to act on the magnetic order of the antiferromagnetic layer, thereby allowing reversal of the magnetic order.