Dipole-Coupled SOT Structure for Lower-Current Magnetic Switching

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Solution Overview

Problem

Conventional spin-orbit torque (SOT) magnetic memories require high write current densities and precise control of magnetic junction shapes, which can lead to thermal instability and fabrication challenges.

Innovation Solution

The integration of a dipole-coupled layer with the magnetic junctions in SOT devices, where the dipole-coupled layer is magnetically coupled to the free layer, enhances the energy barrier and thermal stability, allowing for lower write current densities and improved switching performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If high write current density is used in conventional SOT magnetic memories, then switching performance is improved, but thermal stability deteriorates and energy consumption increases

Engineering Contradiction:

Improveswitching speedVSAvoidthermal stability

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The magnetic structure is segmented into distinct functional layers: a magnetic tunnel junction (MTJ) for data storage and a separate spin-orbit (SO) line for writing operations. This segmentation allows the write current to flow through the SO line rather than directly through the MTJ, reducing the current density required at the magnetic junction while maintaining effective switching through spin-orbit torque generation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The spin-orbit line acts as an intermediary that converts charge current into spin current via the spin Hall effect or Rashba effect. This intermediary mechanism enables indirect switching of the magnetic moment without requiring high current density through the MTJ itself, thus preserving thermal stability while achieving reliable switching performance.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If precise control of magnetic junction shape is implemented, then switching performance is improved, but manufacturing complexity increases

Engineering Contradiction:

Improveswitching performanceVSAvoidfabrication difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The device is segmented into a standard MTJ and a separate SO line structure, where the SO line can be fabricated using conventional photolithography and deposition processes. This segmentation allows each component to be optimized independently, with the SO line shape and dimensions being less critical to overall device performance, thereby simplifying manufacturing while maintaining reliable switching.

Inventive Principle:

Principle #1Segmentation

3Stability of the object's composition

If write current density is reduced to improve thermal stability, then energy barrier is improved, but switching performance deteriorates

Engineering Contradiction:

Improveenergy barrierVSAvoidswitching performance

Core Design Contradiction:

Stability of the object's compositionVSSpeed

Solution Approach 1:

The spin-orbit line serves as an intermediary that generates spin-orbit torque to switch the magnetic moment. By utilizing materials with high spin Hall angles or strong Rashba effects, the system achieves efficient spin current generation from charge current, enabling reliable switching at lower current densities that preserve the energy barrier and thermal stability of the magnetic junction.

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

This configuration increases the effective energy barrier and thermal stability of the magnetic junctions, reducing the required write current density and enhancing switching speed while maintaining stability, thus improving the performance of SOT devices.

Implementation Method 1

The high spin-orbit interaction may be due to a bulk effect of the material itself (spin Hall effect)

Methodology Applied

Scientific EffectSpin Hall Effect: Hall Effect

Implementation Method 2

due to interfacial interactions (Rashba effect)

Methodology Applied

Scientific EffectRashba Effect:

Implementation Method 3

The dipole-coupled layer may be magnetically coupled to the free layer

Methodology Applied

Scientific EffectMagnetic Dipole Coupling: Magnetism

Data Source

PatentUS11776726B2Dipole-coupled spin-orbit torque structure

Publication Date: 2023.10.03 SAMSUNG ELECTRONICS CO LTD

AI summary

A magnetic device is described. The magnetic device includes a magnetic junction, a spin-orbit interaction (SO) line and a dipole-coupled layer. The magnetic junction includes a free layer. The SO line is adjacent to the free layer, carries a current in-plane and exerts a SO torque on the free layer due to the current passing through the SO line. The free layer being switchable between stable magnetic states using the SO torque. The SO line is between the free layer and the dipole-coupled layer. The dipole-coupled layer is magnetically coupled to the free layer. At least one of the free layer and the dipole-coupled layer has a damping of greater than 0.02.