Spin-Orbit Torque Magnetization Rotation via Damping Constant

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Solution Overview

Problem

Magnetization rotational elements using spin-orbit torque (SOT) lack an appropriate configuration for efficient magnetization rotation, differing from those using spin transfer torque (STT), and existing materials with low damping constants face issues with erroneous writing and reliability.

Innovation Solution

Increasing the damping constant of the ferromagnetic metal layer by incorporating materials such as Co and Pt multilayer films, Co-Ni alloys, rare-earth element alloys, and insertion layers with heavy metals, and optimizing the spin-orbit torque wiring configuration to intersect the magnetization direction at specific angles, thereby enhancing magnetization rotation speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the damping constant of the ferromagnetic metal layer is reduced to achieve energy saving and high durability, then energy efficiency improves, but erroneous writing occurs and reliability deteriorates

Engineering Contradiction:

Improveenergy efficiencyVSAvoidwriting reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent changes the damping constant parameter from low (conventional) to high (0.01 or more) to resolve the contradiction. This parameter change enables the system to achieve both energy efficiency and writing reliability by allowing magnetization rotation to occur quickly before thermal fluctuations can cause erroneous writing.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes the dynamic behavior of magnetization rotation speed. By increasing the damping constant, the magnetization rotates more quickly and stabilizes faster, creating a dynamic window for reliable writing before thermal effects can cause errors. This dynamic approach allows the system to maintain both low energy consumption and high reliability.

Inventive Principle:

Principle #15Dynamics

2Ease of operation

If the damping constant is reduced to facilitate magnetization rotation for easier reading and writing, then operation ease improves, but stability of magnetization direction deteriorates

Engineering Contradiction:

Improvemagnetization rotation easeVSAvoidmagnetization direction stability

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent changes the damping constant parameter to 0.01 or more, which creates an optimal balance between magnetization rotation ease and direction stability. The increased damping constant provides sufficient stability to maintain magnetization direction while still allowing rotation to occur under applied torque.

Inventive Principle:

Principle #35Parameter changes

3Speed

If materials with low damping constant are used to achieve high speed magnetization rotation, then rotation speed improves, but erroneous writing increases and reliability decreases

Engineering Contradiction:

Improvemagnetization rotation speedVSAvoiddevice reliability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent changes the damping constant parameter to 0.01 or more, which optimizes the rotation speed to achieve high speed while preventing erroneous writing. The increased damping constant ensures that magnetization rotates quickly but stabilizes reliably, avoiding the errors that occur with overly low damping constants.

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 proposed solution enables quick magnetization rotation with improved reliability and reduced noise, allowing for stable and efficient operation of magnetization rotational elements.

Implementation Method 1

a direction of spin injected from the spin-orbit torque wiring into the ferromagnetic metal layer intersects a magnetization direction of the ferromagnetic metal layer

Methodology Applied

Scientific EffectSpin-orbit interaction:

Implementation Method 2

attention has been focused on magnetization rotation utilizing a pure spin current generated by a spin-orbit interaction as a means for reducing an inversion current

Methodology Applied

Scientific EffectSpin-orbit torque (SOT):

Data Source

PatentUS11107615B2Magnetization rotational element, magnetoresistance effect element, and memory device

Publication Date: 2021.08.31 TDK CORP

AI summary

A magnetization rotational element includes a ferromagnetic metal layer, and a spin-orbit torque wiring extending in a first direction intersecting a lamination direction of the ferromagnetic metal layer and having the ferromagnetic metal layer positioned on one surface thereof, in which a direction of spin injected from the spin-orbit torque wiring into the ferromagnetic metal layer intersects a magnetization direction of the ferromagnetic metal layer, and a damping constant of the ferromagnetic metal layer is larger than 0.01.