Magnetic Memory Cell with Asymmetric Metallization Arms

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Solution Overview

Problem

Existing magnetic memory cells require a current direction-dependent programming method, which limits flexibility and efficiency, as programming operations are tied to the polarity or direction of the current flowing between terminals.

Innovation Solution

A magnetic memory cell design featuring a stack with a magnetic layer and conductive layers positioned on a metallization structure with specific arm configurations, allowing currents to flow in various directions without altering the programming orientation, enabling programming irrespective of current polarity or direction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a current direction-dependent programming method is used in existing magnetic memory cells, then the programming operation can be performed, but the flexibility and efficiency are limited due to the requirement of specific current polarity or direction

Engineering Contradiction:

Improveprogramming flexibilityVSAvoidoperation simplicity

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent introduces an asymmetric nonmagnetic layer with spin-orbit coupling that creates a directional preference for magnetization reversal. This asymmetric structure allows the system to respond differently to current directions, enabling programming flexibility without requiring strict current polarity control. The asymmetric layer generates a transverse spin current that exerts torque on the magnetic layer, facilitating direction-independent programming.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent changes the physical parameters of the memory cell by introducing a nonmagnetic layer with high spin-orbit coupling and specific crystal structure (e.g., body-centered cubic or face-centered cubic). This parameter change enables the system to utilize spin-orbit coupling effects, transforming the programming mechanism from current-direction-dependent to current-magnitude-dependent, thereby improving adaptability and ease of operation.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a magnetic field is applied during programming in existing memory cells, then the magnetization can be oriented, but the device complexity increases and integration becomes more difficult

Engineering Contradiction:

Improvemagnetization orientation controlVSAvoidprogramming structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the external magnetic field system with a spin-orbit coupling-based system. Instead of using mechanical or electromagnetic field generation structures, the patent utilizes the quantum mechanical spin-orbit coupling effect in the nonmagnetic layer to generate the necessary torque for magnetization switching. This substitution eliminates the need for complex magnetic field generation structures, reducing device complexity while maintaining reliable magnetization orientation control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The nonmagnetic layer with spin-orbit coupling serves a dual function: it acts as both the structural component and the active element that generates the switching torque through spin-orbit coupling. The layer essentially serves itself by converting charge current directly into spin torque without requiring external magnetic field assistance, thereby simplifying the overall device structure while maintaining programming reliability.

Inventive Principle:

Principle #25Self-service

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 design allows for flexible and efficient programming of the magnetic memory cell, independent of current direction, and can utilize alternating currents, reducing the required current strength and enhancing integration into electronic components.

Implementation Method 1

the magnetic layer having a magnetization perpendicular to the plane of the layers

Methodology Applied

Scientific EffectPerpendicular magnetic anisotropy: Anisotropy

Implementation Method 2

it is also necessary for spin-orbit couplings to be present in the magnetic layer

Methodology Applied

Scientific EffectSpin-orbit coupling:

Implementation Method 3

reversal of the magnetization in the layer 11 to be possible... material or formed from materials with a high spin-orbit coupling

Methodology Applied

Scientific EffectTopological Hall effect: Hall Effect

Data Source

PatentUS10622046B2Magnetic memory cell

Publication Date: 2020.04.14 CENT NAT DE LA RECH SCI (C N R S)

AI summary

The invention relates to a magnetic memory cell (30), comprising: a stack (31) including a magnetic layer section (34) between a conductive layer section (32) and a section (36) of a layer that is different from the conductive layer, the magnetic layer having a magnetisation (35) perpendicular to the plane of the layers; a metallisation section (42) on which the stack is placed; and first, second, third and fourth metallisation arms (44D to 44G), each arm having a median axis (45D to 45G), wherein, for each arm, a current flowing towards the stack in the direction of the median axis sees that portion of the stack which is closest the arm mostly on its left for the first and second arms (44E, 44G), and mostly on its right for the third and fourth arms (44D, 44F).