Superconductor Magnetic Memory System with Spin-Transfer Torque

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Solution Overview

Problem

Conventional magnetic RAM devices face challenges with high current consumption and slow operation speeds, particularly at high cell densities, which limits their scalability and efficiency.

Innovation Solution

A magnetic memory system utilizing a superconductor circuit and spin-torque magnetic memory elements, where a single flux quantum comparator circuit generates and transmits magnetic signals with low energy, enabling high-speed data access and storage with reduced current consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If conventional field-switched MRAM uses Amperian fields from current-carrying wires to reorient magnetic layers, then data storage is achieved, but high current consumption occurs

Engineering Contradiction:

Improvecurrent consumptionVSAvoiddata storage reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent replaces the conventional Amperian field mechanism (current-carrying wires generating magnetic fields) with a spin-polarized electron tunneling mechanism. The spin valve structure uses spin-aligned electrons to directly transfer angular momentum to the magnetic layers, substituting the mechanical/electromagnetic field approach with a quantum spin transport approach, thereby reducing current consumption while maintaining data storage functionality

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental operating parameter from high current density in conventional wires to low current density through the spin valve tunnel barrier. By modifying the magnetic tunnel junction parameters (barrier thickness, material composition) and spin polarization degree, the system achieves efficient spin transfer torque with significantly reduced current consumption compared to conventional field switching

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If STT uses spin-aligned electrons to apply torque directly to magnetization, then write current is reduced, but device size must be smaller than spin-diffusion length

Engineering Contradiction:

Improvewrite currentVSAvoiddevice size

Core Design Contradiction:

Use of energy by moving objectVSLength of moving object

Solution Approach 1:

The patent applies local quality by creating a highly spin-polarized current path through the spin valve structure with specific local material properties. The spin diffusion length is effectively extended locally through the tunnel barrier region where spin polarization is maintained, allowing the device to operate at the optimal size scale for spin transfer torque while achieving reduced write currents through localized spin accumulation and enhanced spin polarization at the magnetic interface

Inventive Principle:

Principle #3Local quality

3Quantity of substance

If magnetic memory devices are scaled to high cell densities, then storage capacity increases, but current consumption and operation speed deteriorate

Engineering Contradiction:

Improvestorage capacityVSAvoidoperation speed

Core Design Contradiction:

Quantity of substanceVSProductivity

Solution Approach 1:

The patent replaces the conventional slow Amperian field switching mechanism with the faster spin transfer torque mechanism enabled by the spin valve structure. This substitution allows high-speed magnetization switching even at high cell densities, as the spin-polarized electron tunneling process occurs on femtosecond timescales, maintaining operation speed while enabling increased storage capacity through higher cell density integration

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 system achieves high-speed data access and storage with significantly lower energy consumption, facilitating the development of smaller, more efficient magnetic memory devices.

Implementation Method 1

a single flux quantum comparator circuit generates a magnetic signal for transmission over a link to the magnetic memory element

Methodology Applied

Scientific EffectSingle flux quantum: Josephson Effect

Implementation Method 2

Each of the layers has a magnetization vector that can point in one of several directions, storing a magnetization state

Methodology Applied

Scientific EffectMagnetization: Ferromagnetism

Implementation Method 3

STT-RAM differs from conventional MRAM by utilizing the torque exerted by an ensemble of spin-polarized electrons (or holes) to effect a rotation of the free layer through a short-range exchange interaction

Methodology Applied

Scientific EffectSpin transfer torque:

Implementation Method 4

Magnetoresistance is a measure of the resistance of the magnetic device. A magnitude of the magnetoresistance depends on the relative alignment of the magnetization of two or more layers

Methodology Applied

Scientific EffectMagnetoresistance: Magnetoresistance

Data Source

PatentUS9286962B2Magnetic memory system and methods in various modes of operation

Publication Date: 2016.03.15 RTX BBN TECH INC

AI summary

A magnetic memory system includes a superconductor circuit and one or more magnetic memory elements to store data. To write data, a driver circuit in the superconductor circuit generates a magnetic signal for transmission over a superconductor link extending between the superconductor circuit and the magnetic memory element. To read data, a sensing circuit in the superconductor circuit monitors a superconductor link extending from sensing circuit to the magnetic memory element. The magnetic memory element can be a spin-transfer type magnetic memory element.