Magnetic Domain Wall Propagation via Spin Torque Injection

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Solution Overview

Problem

Existing magnetic domain wall memory devices require external magnetic fields to generate and propagate domain walls, which is inefficient and difficult to scale down, and introduce process variability and increased costs.

Innovation Solution

A method to generate a stream of domain walls along a magnetic bus without an external magnetic field by using a device with a magnetic propagation layer featuring converging magnetic buses with opposite magnetization states, where spin orbit or transfer torques alternate a pinned domain wall between stable configurations, allowing for efficient domain wall injection and propagation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If external magnetic fields are used to generate and propagate domain walls, then domain wall motion can be achieved, but current and energy requirements increase and device scalability decreases

Engineering Contradiction:

Improvecurrent and energy requirementsVSAvoiddevice scalability

Core Design Contradiction:

Use of energy by moving objectVSEase of operation

Solution Approach 1:

The patent extracts and eliminates the external magnetic field from the system by using an in-plane magnetized region within the magnetic strip itself to generate the necessary magnetic field for domain wall injection. This removes the need for external magnetic field sources and reduces current requirements.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces an in-plane magnetized region as an intermediary element within the magnetic strip that mediates the generation of domain walls. This intermediate structure converts applied current into localized magnetic fields that propagate domain walls without requiring external magnetic field sources.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If external magnetic fields are applied to generate domain walls, then domain wall propagation is enabled, but process variability and manufacturing costs increase

Engineering Contradiction:

Improveprocess control and manufacturing consistencyVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges the domain wall generation function into the magnetic strip structure itself by integrating an in-plane magnetized region. This consolidation eliminates separate external magnetic field generation components and their associated process variability, simplifying manufacturing while improving reliability.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of operation

If conventional magnetic field methods are used for domain wall injection, then domain walls can be generated, but device footprint and structural complexity increase

Engineering Contradiction:

Improvedevice footprintVSAvoidstructural complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent implements a nested structure where the in-plane magnetized region is embedded within the magnetic strip itself. This nested configuration allows the domain wall generation mechanism to be contained within the existing device footprint, eliminating the need for external magnetic field sources and reducing overall structural complexity.

Inventive Principle:

Principle #7Nested doll (Nesting)

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

Enables efficient and scalable generation of domain walls for data recording in domain wall memory devices, reducing current and energy requirements, and allowing for flexible bit sequences to be converted into magnetic domain streams without the need for external magnetic fields.

Implementation Method 1

An applied current may generate a spin-polarized current that may move the domain wall along the magnetic strip by applying a spin transfer torque

Methodology Applied

Scientific EffectSpin transfer torque:

Implementation Method 2

a spin-coherent electric current may be used to move a sequence of magnetic domains through a substrate, e.g., along a magnetic bus

Methodology Applied

Scientific EffectSpin-orbit torque:

Data Source

PatentUS10236046B2Method of propagating magnetic domain wall in magnetic devices

Publication Date: 2019.03.19 INTERUNIVERSITAIR MICRO ELECTRONICS CENT (IMEC VZW)

AI summary

The disclosed technology generally relates to magnetic devices, and more particularly to magnetic devices configured to generate a stream of domain walls propagating along an output magnetic bus. In an aspect, a magnetic device includes a magnetic propagation layer, which in turn includes a plurality of magnetic buses. The magnetic buses include an output magnetic bus configured to guide propagating magnetic domain walls. The magnetic propagation layer further comprises a central region in which the magnetic buses converge and are joined together. The magnetic buses include at least a first and a second magnetic bus having opposite magnetization orientations with respect to each other, such that a domain wall separating the opposite magnetization states is pinned in the central region. In another aspect, a method includes providing the magnetic device and generating the stream of domain walls propagating along the output magnetic bus by applying spin orbit and/or transfer torques to the pinned domain wall to alternate the pinned domain wall between two stable configurations, in which each stable configuration corresponds to a different magnetization state of the output magnetic bus in at least a region where the output magnetic bus is joined to the central region.