Spin-Orbit Torque Magnetic Memory Switching

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Solution Overview

Problem

Conventional spin transfer torque random access memories (STT-RAMs) face challenges with high write error rates and require high currents for switching, especially at shorter write current pulses, which can lead to unacceptably high write error rates and issues with dual magnetic tunneling junctions due to magnetoresistance cancellation and difficulties in growing suitable crystal structures.

Innovation Solution

Incorporating a spin-orbit interaction (SO) active layer adjacent to the magnetic junctions to exert a spin-orbit torque on the data storage layer, allowing for switching using a current passing through the SO active layer in a direction perpendicular to the data storage layer, which assists in reducing switching time and improving write error rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional spin transfer torque is used for switching, then the magnetic junction can be written, but high currents are required leading to high write error rates especially at shorter pulse widths

Engineering Contradiction:

Improvewrite error rateVSAvoidcurrent density

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

A spin-orbit interaction layer is introduced as an intermediary between the current path and the data storage layer. This layer converts charge current into spin-orbit torque that acts on the magnetic moments, enabling switching at lower current densities and reducing write error rates without requiring high direct current through the magnetic junction

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The conventional spin transfer torque mechanism (direct spin-polarized current through magnetic layers) is replaced with a spin-orbit interaction mechanism. This substitution uses spin-orbit coupling effects to generate the necessary torque on magnetic moments, achieving more efficient and reliable switching with lower energy consumption

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If dual magnetic tunneling junctions are used, then switching capability is enhanced, but magnetoresistance cancellation occurs and crystal structure growth becomes difficult

Engineering Contradiction:

Improveswitching capabilityVSAvoidmagnetoresistance signal

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The spin-orbit interaction layer is extracted from the conventional magnetic junction stack and positioned adjacent to the data storage layer. This separation allows the dual junction architecture to function without magnetoresistance cancellation, as the spin-orbit torque is applied locally to each junction's data storage layer independently, preserving the read signal integrity

Inventive Principle:

Principle #2Taking out (Extraction)

3Speed

If high currents are applied for switching, then the magnetic moment can be switched, but the magnetic junction may be damaged and energy consumption increases

Engineering Contradiction:

Improveswitching speedVSAvoidjunction durability

Core Design Contradiction:

SpeedVSStrength

Solution Approach 1:

The spin-orbit interaction layer serves as a mediator that converts electrical current into mechanical torque on the magnetic moments through spin-orbit coupling. This indirect mechanism allows switching to occur at lower current densities, preventing junction damage while maintaining fast switching speeds through efficient torque generation

Inventive Principle:

Principle #24Intermediary (Mediator)

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 use of spin-orbit interaction enhances the switching efficiency and reduces write time, improving write error rates and allowing for faster programming of magnetic memories with lower current densities, thus overcoming the limitations of conventional STT-RAMs.

Implementation Method 1

Each of the magnetic junctions includes a data storage layer that is magnetic. The SO active layer(s) are adjacent to the data storage layer of the magnetic junction. The at SO active layer(s) are configured to exert a SO torque on the data storage layer due to a current passing through the at least one SO active layer

Methodology Applied

Scientific EffectSpin-orbit interaction:

Implementation Method 2

The current carriers are spin polarized and exert a torque on the magnetization 21 of the conventional free layer. The spin transfer torque on the magnetic moment 21 of the conventional free layer 20 is initially small when the magnetic moment 21 is parallel to the easy axis

Methodology Applied

Scientific EffectSpin transfer torque:

Data Source

PatentUS9076537B2Method and system for providing a magnetic tunneling junction using spin-orbit interaction based switching and memories utilizing the magnetic tunneling junction

Publication Date: 2015.07.07 SAMSUNG ELECTRONICS CO LTD

AI summary

A magnetic memory is described. The magnetic memory includes magnetic junctions and at least one spin-orbit interaction (SO) active layer. Each of the magnetic junctions includes a data storage layer that is magnetic. The SO active layer(s) are adjacent to the data storage layer of the magnetic junction. The at SO active layer(s) are configured to exert a SO torque on the data storage layer due to a current passing through the at least one SO active layer in a direction substantially perpendicular to a direction between the at least one SO active layer and the data storage layer of a magnetic junction of the plurality of magnetic junctions closest to the at least one SO active layer. The data storage layer is configured to be switchable using at least the SO torque.