Multi-Terminal TMR Sensor for Extended Magnetic Field Range
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Solution Overview
Problem
Conventional magnetoresistance elements have limited operational ranges and sensitivity, restricting their use to low-strength magnetic fields, and suffer from current-induced degradation due to temperature increases beyond the blocking temperature.
Innovation Solution
A tunnel magnetoresistance (TMR) sensor design with a multi-terminal configuration, utilizing a conductive material layer and TMR elements where currents flow through the bottom layer without passing through the barrier layer, maintaining it below the blocking temperature to prevent degradation, and employing a thermal diode for temperature control, and a heavy metal layer to generate a transversal spin current for resistance modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional magnetoresistance elements are used to detect magnetic fields, then sensitivity is improved, but operational range is limited to the linear region
Solution Approach 1:
The sensing element is divided into multiple independent magnetoresistance elements arranged in an array. Each element operates in its linear region but responds to different portions of the magnetic field vector. By segmenting the sensing function across multiple elements with different orientation relationships to the magnetic field, the system achieves both high sensitivity (each element operating in linear region) and extended operational range (collective response covers broader field strengths and directions).
Solution Approach 2:
The patent transitions from scalar magnetic field sensing to vector magnetic field sensing by arranging magnetoresistance elements in specific geometric configurations. This dimensional expansion allows the sensor array to detect both magnitude and direction of magnetic fields, effectively extending the operational range while maintaining sensitivity through operation within the linear region of each individual element.
2Measurement precision
If current is increased to improve sensitivity, then measurement precision is improved, but thermal degradation occurs beyond blocking temperature
Solution Approach 1:
The current path is segmented into two separate circuits: a first current flows through the barrier layer to generate the TMR effect, while a second current flows through the bottom layer to provide thermal stabilization. This segmentation allows independent optimization of each current's function - the first current maintains sensitivity while the second current prevents thermal degradation by stabilizing the bottom layer temperature below the blocking temperature.
Solution Approach 2:
The bottom layer acts as a thermal intermediary between the TMR element and the substrate. By routing a stabilizing current through this intermediate layer, the system can control the thermal profile of the TMR element, preventing excessive heating that would cause degradation while maintaining the conditions necessary for high-sensitivity operation.
3Device complexity
If conventional two-terminal configuration is used, then device complexity is reduced, but functional versatility is limited
Solution Approach 1:
The multi-terminal configuration enables the same physical structure to perform multiple functions: the first current path provides magnetic field sensing through the TMR effect, while the second current path provides thermal stabilization. This multi-functionality allows a single device structure to simultaneously achieve sensitivity enhancement and thermal management, increasing functional versatility without requiring separate independent systems.
Solution Approach 2:
The patent introduces dynamic control capabilities by enabling independent adjustment of the first and second currents. This dynamic flexibility allows the sensor to adapt its operating characteristics in real-time, optimizing sensitivity for different magnetic field conditions while maintaining thermal stability, thereby enhancing functional versatility beyond fixed two-terminal configurations.
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 TMR sensor extends the operational range beyond the linear region of magnetoresistance elements, maintaining sensitivity and preventing current-induced degradation, enabling accurate magnetic field sensing across a broader range while maintaining high sensitivity and preventing thermal drift.
Implementation Method 1
a tunnel magnetoresistance (TMR) element positioned on and in electrical contact with the conductive material layer
Implementation Method 2
employing a thermal diode for temperature control, and a heavy metal layer to generate a transversal spin current for resistance modulation
Implementation Method 3
A first current is configured to flow from the first metal layer portion, through the conductive material layer, to the second metal layer portion
Data Source
AI summary
In one aspect, a sensor includes a first metal layer portion and a second metal layer portion separated by an insulator material; a conductive material layer in electrical contact with the first metal layer portion and the second metal layer portion; and a tunnel magnetoresistance (TMR) element positioned on and in electrical contact with the conductive material layer. A first current is configured to flow from the first metal layer portion, through the conductive material layer, to the second metal layer portion, and a second current is configured to flow from the first metal layer portion, through the conductive material layer, through the TMR element, and exiting through a top of the TMR element.