Antiparallel Ferromagnetic Sensor for Weak Magnetic Field Detection
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Solution Overview
Problem
Existing devices for measuring weak magnetic fields face challenges in construction, size, and implementation, particularly in detecting fields weaker than one picotesla, and require complex sensor configurations.
Innovation Solution
The use of sensors comprising two ferromagnetic layers separated by a tunnel insulating barrier layer, with magnetizations oriented antiparallel and shaped to enhance magnetostatic coupling, allowing for sensitive detection of weak magnetic fields without additional ferromagnetic elements, making the sensors simple to produce and integrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex sensor configurations are used to detect weak magnetic fields, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The sensor is segmented into distinct functional layers: ferromagnetic layers for magnetic field interaction, tunnel insulating barrier layers for magnetic isolation, and conductive layers for electrical connection. This segmentation allows each layer to perform its specific function efficiently, achieving high sensitivity while maintaining manufacturing simplicity
Solution Approach 2:
The sensor employs composite material structure combining ferromagnetic materials with tunnel insulating barrier materials and conductive materials. This composite approach enables the sensor to detect weak magnetic fields through magnetoresistance effects while avoiding the need for additional ferromagnetic elements or complex compensation circuits
2Measurement precision
If additional ferromagnetic elements are added to enhance sensitivity, then measurement precision is improved, but manufacturing complexity increases
Solution Approach 1:
The invention extracts and eliminates the need for additional ferromagnetic elements by utilizing the intrinsic magnetoresistance properties of the ferromagnetic layers already present in the sensor structure. The tunnel insulating barrier layers provide sufficient magnetic isolation, making extra ferromagnetic components redundant
Solution Approach 2:
The ferromagnetic layers serve multiple functions: they provide magnetic field sensing capability, generate magnetostatic coupling for sensitivity enhancement, and eliminate the need for separate compensation circuits. This multi-functionality achieves high sensitivity without adding manufacturing complexity
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 results in highly sensitive magnetic field sensors that are easy to implement and provide precise measurements, capable of detecting magnetic fields of the order of hundred pT, regardless of field direction, without the need for additional compensation circuits.
Implementation Method 1
shaped to enhance magnetostatic coupling, allowing for sensitive detection of weak magnetic fields
Implementation Method 2
device for measuring weak magnetic fields comprising two stacks superimposed on one another and comprising, respectively, two ferromagnetic layers with magnetizations oriented in the plane of the layers and in an antiparallel configuration
Data Source
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AI summary
The invention relates to a device for measuring a magnetic field, comprising a magnetic circuit having two substantially parallel branches (102A, 102B) in which magnetic fluxes (HA, HB) flow in opposite directions; and a sensor (200A, 200B) situated in each of the branches, comprising a stack of two ferromagnetic layers (202, 204) separated by a tunnel insulating barrier layer (206), the ferromagnetic layers having magnetizations (216, 218) that are oriented in the plane of the layers, each of the two ferromagnetic layers being magnetically coupled only in antiparallel with the other of the two ferromagnetic layers, on the one hand, and to one of the magnetic fluxes and to the magnetic field to be measured, on the other hand.