Spin-Orbit Torque Random Number Generator

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Solution Overview

Problem

Existing random number generators face issues such as increased size due to the need for amplifier circuits and threshold circuits, limited operation speed, and susceptibility to external factors, particularly in generators using spin transfer torque (STT) that rely on narrow margins of current and magnetic fields.

Innovation Solution

A random number generator utilizing spin-orbit torque (SOT) is developed, comprising a ferromagnetic metal layer and spin-orbit torque wiring where the spin injection direction and easy magnetization direction intersect, allowing for natural random number generation with improved miniaturization and resistance to external influences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If noise amplification and binarization circuits are added to generate natural random numbers, then random number quality is improved, but device size increases

Engineering Contradiction:

Improverandom number qualityVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent extracts and eliminates the amplifier circuit and threshold circuit from the random number generation system. Instead of using separate circuits for noise amplification and binarization, the invention uses the intrinsic properties of the tunnel junction device to directly generate binarized random numbers, thereby reducing device size while maintaining random number quality

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The tunnel junction device is designed to perform multiple functions simultaneously: it generates noise, amplifies the noise, and binarizes the signal all within a single device structure. This multi-functionality eliminates the need for separate amplifier and threshold circuits, resolving the contradiction between random number quality and device size

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If spin transfer torque (STT) is used for random number generation, then natural random number generation is achieved, but the device becomes susceptible to external factors due to narrow current and magnetic field margins

Engineering Contradiction:

Improverandom number generation capabilityVSAvoidsusceptibility to external factors

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the operating parameters by using spin-orbit torque (SOT) instead of spin transfer torque (STT). This parameter change involves switching from a mechanism that requires precise control of current and magnetic field margins to one that uses spin Hall effect, thereby reducing susceptibility to external factors while maintaining random number generation capability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces a spin-orbit torque wiring as an intermediary element that generates spin current through the spin Hall effect. This intermediary mechanism decouples the random number generation process from direct sensitivity to external magnetic fields and current margin constraints, reducing susceptibility to external factors

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If tunnel junction noise is used for random number generation, then natural random numbers are generated, but operation speed is limited to 100 kbit/sec

Engineering Contradiction:

Improvenatural random number generationVSAvoidoperation speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies preliminary action by pre-configuring the tunnel junction device with specific structural parameters (barrier thickness, layer composition) that enable both high-speed operation and natural random number generation. The device is designed in advance to operate without requiring slow external amplification and binarization processes, thereby achieving both natural random number generation and high operation speed

Inventive Principle:

Principle #10Preliminary action

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 SOT-based random number generator achieves efficient natural random number generation with enhanced speed and stability, eliminating the need for delicate current adjustments and external magnetic field reliance, while maintaining 50% probability for '1' and '0' occurrences.

Implementation Method 1

a spin-orbit torque wiring extending in a first direction intersecting a lamination direction of the ferromagnetic metal layer and being joined to the ferromagnetic metal layer, wherein a direction of spin injected from the spin-orbit torque wiring into the ferromagnetic metal layer and an easy magnetization direction of the ferromagnetic metal layer intersect each other

Methodology Applied

Scientific EffectSpin Hall Effect: Hall Effect

Data Source

PatentUS10574215B2Random number generator, random number generation device, neuromorphic computer, and quantum computer

Publication Date: 2020.02.25 TDK CORP

AI summary

A random number generator capable of generating a natural random number using a spin-orbit torque (SOT) is provided. The random number generator includes a ferromagnetic metal layer and a spin-orbit torque wiring extending in a first direction crossing a lamination direction of the ferromagnetic metal layer and being joined to the ferromagnetic metal layer, wherein the direction of spins injected from the spin-orbit torque wiring into the ferromagnetic metal layer and an easy magnetization direction of the ferromagnetic metal layer intersect each other.