Spin-orbit torque enhancement via ultra-thin insertion layers

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Solution Overview

Problem

Current technologies face challenges in enhancing spin current and spin-orbit torque generation for advanced magnetic memory, logic, and oscillator applications, with limited efficiency and high power consumption due to the limitations in spin Hall effect metals.

Innovation Solution

The introduction of ultra-thin insertion layers of Hf or Ti within the spin Hall metals, such as Pt, to increase interfacial scattering and enhance resistivity, leading to a significant increase in dampinglike spin-orbit torque efficiency without degrading the intrinsic spin Hall conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If ultra-thin insertion layers (Hf or Ti) are introduced within spin Hall metals to increase interfacial scattering, then spin-orbit torque efficiency is enhanced, but device complexity increases

Engineering Contradiction:

Improvespin-orbit torque efficiencyVSAvoiddevice complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The patent embeds ultra-thin insertion layers (Hf or Ti) within the spin Hall metal layer, creating a nested multilayer structure where the insertion layers are positioned at specific interfaces to enhance spin-orbit torque efficiency through interfacial scattering without significantly increasing overall device complexity

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The insertion layers are strategically placed only at specific interfaces where they are needed to enhance spin scattering, rather than uniformly distributing the scattering mechanism throughout the entire spin Hall metal layer, thus achieving localized improvement in torque efficiency

Inventive Principle:

Principle #3Local quality

2Productivity

If ultra-thin insertion layers are introduced to enhance resistivity through interfacial scattering, then spin current is enhanced, but manufacturing precision requirements increase

Engineering Contradiction:

Improvespin currentVSAvoidmanufacturing precision

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent modifies the resistivity parameter of the spin Hall metal layer by introducing ultra-thin insertion layers with specific materials (Hf or Ti) at controlled thicknesses (0.2-2.0 nm), thereby changing the electronic scattering properties to enhance spin current while maintaining manufacturability through standard thin-film deposition techniques

Inventive Principle:

Principle #35Parameter changes

3Power

If insertion layers are used to increase spin-orbit torque efficiency, then switching current density is reduced, but energy loss increases

Engineering Contradiction:

Improveswitching current densityVSAvoidenergy loss

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent converts the potentially harmful effect of increased scattering (which could cause energy loss) into a beneficial mechanism by using the insertion layers to enhance spin-dependent scattering specifically, thereby reducing the switching current density and improving torque efficiency while the increased resistivity is localized and managed

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 approach results in a substantial enhancement of spin-orbit torque efficiency, enabling deterministic magnetic switching at lower current densities and reduced power consumption, making it suitable for low-power spin-torque devices.

Implementation Method 1

a spin Hall effect metal layer including a metal exhibiting a large spin Hall effect (SHE) to react to a charge current directed into the spin Hall effect metal layer to produce a spin-polarized current that is perpendicular to the charge current

Methodology Applied

Scientific EffectSpin Hall Effect: Hall Effect

Implementation Method 2

the spin Hall effect metal layer includes one or more insertion metal layers to interface with the MTJ to introduce interfacial scattering of electrons

Methodology Applied

Scientific EffectInterfacial scattering: Scattering

Implementation Method 3

a non-magnetic junction layer between the magnetic free layer and the pinned magnetic layer and formed of an insulator material sufficiently thin to allow tunneling of electrons between the magnetic free layer and the pinned magnetic layer

Methodology Applied

Scientific EffectQuantum tunneling:

Implementation Method 4

a spin-polarized current can be directed into a magnetic layer to cause transfer of the angular momenta of the spin-polarized electrons to the magnetic layer and this transfer can lead to exertion of a spin-transfer torque (STT) on the local magnetic moments in the magnetic layer

Methodology Applied

Scientific EffectSpin-transfer torque:

Data Source

PatentUS11444240B2Giant enhancement of spin-orbit torque by interface scattering from ultra-thin insertion layers

Publication Date: 2022.09.13 CORNELL UNIVERSITY

AI summary

Methods, systems, and devices are disclosed for enhancement of spin-orbit torque. In one aspect, a magnetic device includes a magnetic tunneling junction (MTJ), including a free magnetic layer, a pinned magnetic layer and a non-magnetic junction layer between the free magnetic layer and the pinned magnetic layer, and a spin Hall effect metal layer that includes one or more insertion metal layers operable to introduce interfacial scattering of electrons flowing in the spin Hall metal layer to increase the spin current that interacts with and changes the magnetization of the free magnetic layer of the MTJ.