TMR Sensor Shifting Layer for Wider Magnetic Field Range
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Solution Overview
Problem
TMR sensors with an out-of-plane sensitivity axis and vortex configuration suffer from non-negligible hysteresis, reduced accuracy, reproducibility, and decreased measurement range due to vortex core polarity switching field decrease with temperature.
Innovation Solution
Incorporating a shifting layer with a hard magnetic material adjacent to the sense layer to induce a stray field, which increases the vortex core polarity switching field, thereby improving the TMR element's robustness and measurement range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a vortex configuration is used in the sense layer to achieve wider magnetic field range and better linearity, then the measurement range is improved, but hysteresis increases and measurement precision deteriorates
Solution Approach 1:
A shifting layer is introduced as an intermediary component between the sense layer and the external environment. This shifting layer generates a stray magnetic field that acts as a mediator to adjust the effective magnetic field experienced by the vortex core, thereby compensating for hysteresis effects and improving measurement precision without reducing the overall measurement range
2Adaptability or versatility
If the vortex core polarity switching field is increased to improve measurement range, then the field range is expanded, but the device complexity increases
Solution Approach 1:
The magnetic anisotropy energy parameter of the sense layer is modified by introducing the shifting layer with specific magnetic properties. This parameter change increases the vortex core polarity switching field, thereby expanding the measurement range. The solution achieves this through material selection and layer configuration rather than complex structural modifications
3Temperature
If temperature increases, then the vortex core polarity switching field decreases, but this leads to reduced measurement range and reliability
Solution Approach 1:
The shifting layer is designed to generate a stray magnetic field that preliminarily counteracts the thermal effects on the vortex core. By pre-compensating for the temperature-induced decrease in switching field, the system maintains reliable and reproducible measurements across a wide temperature range, preventing the deterioration of measurement quality before it occurs
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 addition of the shifting layer enhances the vortex core polarity switching field, leading to improved accuracy, reproducibility, and expanded measurement range of the TMR sensor.
Implementation Method 1
the shifting layer being configured to induce a stray field on the sense layer and increases the vortex core polarity switching field
Implementation Method 2
A tunnel magnetoresistance (TMR) sensor utilizing a TMR element provides high magnetic sensitivity... The electrical resistance of the TMR element changes along with this change in the free layer
Implementation Method 3
The coupling layer is configured to produces an antiferromagnetically coupling between the first and second reference magnetization such that the second reference magnetization remains antiparallel to the first reference magnetization
Data Source
AI summary
The present disclosure concerns a tunnel magnetoresistance (TMR) element comprising a tunnel barrier layer sandwiched between a reference layer having a pinned reference magnetization and a sense layer having a sense magnetization that is orientable relative to the fixed reference magnetization in the presence of an external magnetic field. The sense magnetization comprises a stable vortex configuration having a vortex core magnetization polarity that is reversed when a vortex core polarity switching field is applied on the TMR element. The TMR element further comprises a shifting layer adjacent to the sense layer, the shifting layer having a shifting magnetization, the shifting layer being configured to induce a stray field on the sense layer and increases the vortex core polarity switching field. The present disclosure further concerns a TMR sensor comprising a plurality of the TMR elements. The TMR element and TMR sensor have improved robustness and field of application.