Magnetic Memory Point for Linear Field Sensing

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Solution Overview

Problem

Existing magnetic sensors and memories based on tunnel magnetoresistance principle face challenges in achieving linear magnetic field sensor functionality due to differing alignment requirements for memory and sensor operations, leading to compromised co-integration of both functionalities in the same substrate.

Innovation Solution

A method is developed to extend the functionality of a magnetic memory point with perpendicular interface anisotropy to include linear magnetic field sensing by using a magnetic tunnel junction with a storage layer and a reference layer, where the intensity of an external magnetic field is measured by successively applying currents or voltages until magnetisation switching occurs, and determining the minimum switching current or voltage value.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If magnetic memory points with perpendicular interface anisotropy are used for information storage, then memory functionality is achieved, but linear magnetic field sensor functionality is compromised due to differing alignment requirements

Engineering Contradiction:

Improvedual functionality (memory and sensor)VSAvoidsensor linearity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies multi-functionality by enabling magnetic memory points with perpendicular interface anisotropy to serve dual purposes: information storage and linear magnetic field sensing. The same magnetic tunnel junction structure is used for both functions, with the sensing achieved by measuring resistance changes in response to external magnetic fields while maintaining the perpendicular magnetization configuration optimized for memory operation.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent employs parameter changes by utilizing the resistance-magnetic field relationship in the perpendicular magnetization regime. By measuring resistance variations as a function of applied magnetic field and identifying characteristic switching points or linear response regions, the system extracts sensor functionality from the memory structure without altering its fundamental perpendicular anisotropy configuration.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If magnetic tunnel junction is used with storage layer and reference layer, then both memory and sensing functionalities are realized, but device complexity increases

Engineering Contradiction:

Improvesimultaneous memory and sensing operationVSAvoidmagnetic layer structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges memory and sensor functionalities into a single magnetic tunnel junction device. The storage layer, reference layer, and tunnel barrier layer form an integrated structure that performs both information storage (through magnetization states) and magnetic field sensing (through resistance changes), eliminating the need for separate sensor and memory components.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The magnetic tunnel junction is designed as a universal component that simultaneously provides memory functionality through its bistable magnetization states and sensor functionality through its magnetoresistive response to external fields, maximizing the utility of the complex layered structure.

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 approach allows for the simultaneous realization of information storage and magnetic field sensing functionalities without compromising either, with the ability to adjust sensor properties like sensitivity and field range by modifying the sensor area, and achieving a small overall size.

Implementation Method 1

magnetic sensors and memories operating by means of the tunnel magnetoresistance principle

Methodology Applied

Scientific EffectTunnel magnetoresistance: Magnetoresistance

Implementation Method 2

a write mechanism based on spin transfer torque

Methodology Applied

Scientific EffectSpin transfer torque:

Implementation Method 3

The magnetic field Heff acting on the storage layer 101 results from the sum of the external field and the dipole field created by the reference layer 107

Methodology Applied

Scientific EffectMagnetic field interaction: Magnetic Field

Data Source

PatentUS12292486B2Method for measuring an external magnetic field by at least one magnetic memory point

Publication Date: 2025.05.06 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

AI summary

A method for measuring the intensity of an external magnetic field by using a magnetic memory point including a storage layer having a magnetisation switchable between two magnetisation directions substantially perpendicular to the plane of the layer; a reference layer having a fixed magnetisation perpendicular to the plane of the layer; and a tunnel barrier layer separating the storage layer and the reference layer; the method including successively applying a plurality of currents or voltages of different amplitudes to the memory point until switching of the magnetisation direction of the storage layer takes place to determine a minimum switching current value of the magnetisation direction of the storage layer or a minimum switching voltage value of the magnetisation direction of the storage layer, and determining the intensity of the external magnetic field to be measured from the minimum switching current value or the minimum switching voltage value.