Spin Transfer Torque Memory Device Using Topological Insulator Layers

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Solution Overview

Problem

Existing spin transfer torque (STT) magnetic memory devices have inefficiencies in switching magnetization direction due to significant reflection of spin-polarized electrons, leading to high resistance and energy dissipation.

Innovation Solution

A spin transfer torque magnetic memory device is designed with alternating layers of topological insulator layers and insulator layers, sandwiching a magnetic material, where an electric field generates spin-polarized electrons orthogonal to the current, allowing for controlled magnetization direction through spin torque, eliminating the need for hard magnetic materials and reducing energy dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a magnetization layer is used as a source of spin-polarized electrons, then spin-polarized current can be generated, but about half of the spin-polarized electrons are reflected resulting in relatively large resistance across the fixed layer

Engineering Contradiction:

Improveenergy dissipationVSAvoidspin torque transfer efficiency

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent changes the material parameter from conventional ferromagnetic fixed layer to topological insulator material, which fundamentally alters the spin polarization mechanism. This parameter change eliminates electron reflection and achieves 100% spin polarization efficiency, resolving the contradiction between energy loss and transfer efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite structure consisting of topological insulator layers alternating with insulator layers. This composite material approach enables the generation of spin-polarized electrons without reflection, simultaneously reducing energy dissipation and improving spin torque transfer efficiency

Inventive Principle:

Principle #40Composite materials

2Reliability

If alternating layers of topological insulator layers and insulator layers are used, then spin-polarized electrons can be generated along the surface, but device structure becomes more complex

Engineering Contradiction:

Improvemagnetization controlVSAvoidlayered structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the device into alternating layers of topological insulator and insulator materials. This segmentation allows the topological insulator layers to generate spin-polarized electrons while insulator layers provide electrical isolation, achieving superior magnetization control through a modular layered architecture

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The topological insulator layers serve multiple functions: generating spin-polarized electrons, providing spin torque, and enabling magnetization control. This multi-functionality reduces the need for separate components, offsetting the structural complexity with functional integration

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 enhances the control of magnetization direction, reduces energy loss, and improves spin torque transfer efficiency, enabling cost-effective and efficient operation with improved magnetic properties for both digital and analog applications.

Implementation Method 1

an electric field generates spin-polarized electrons orthogonal to the current, allowing for controlled magnetization direction through spin torque

Methodology Applied

Scientific EffectSpin-polarized electron generation:

Implementation Method 2

the direction of magnetization of the magnetic material is controllable through transfer of spin of spin-polarized electrons by torque caused by the spin of spin-polarized electrons on the direction of magnetization

Methodology Applied

Scientific EffectSpin torque:

Data Source

PatentUS9281040B2Spin transfer torque magnetic memory device

Publication Date: 2016.03.08 INTERUNIVERSITAIR MICRO ELECTRONICS CENT (IMEC VZW)

AI summary

A spin transfer torque magnetic memory device is disclosed. In one aspect, the spin transfer torque magnetic memory device comprises a first layered structure stacked in a vertical direction and comprising alternating topological insulator layers and insulator layers. The memory device additionally includes a second layered structure stacked in the vertical direction and comprising alternating topological insulator layers and insulator layers. The memory device further includes a magnetic material interposing the first and second layered structures in a horizontal direction different from the vertical direction such that the magnetic material is in contact with a first side surface of the first layered structure and in contact with a first side surface of the second layered structure. Additionally, the magnetic material is configured to have a magnetization direction that can change in response to a current flowing through the magnetic material.