Vortex Magnetoresistive Sensor Pinning for Wide Linear Response
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Solution Overview
Problem
Vortex-based magnetic sensor devices typically operate well at low magnetic fields but experience performance changes and zero-field offset shifts when subjected to high magnetic fields, limiting their accuracy and linear response range.
Innovation Solution
A magnetoresistive element with a stable vortex configuration in the sense layer, pinned by a sense pinning layer with a specific exchange-bias strength, and a reference layer pinned by a reference pinning layer, allowing the element to maintain performance across high magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If vortex-based magnetic sensor devices are subjected to high magnetic fields, then the magnetic field sensing capability is enhanced, but performance changes and zero-field offset shifts occur, reducing measurement precision
Solution Approach 1:
The patent divides the pinning function into two separate layers: a reference pinning layer for the reference layer and a sense pinning layer for the sense layer. This segmentation allows independent optimization of each layer's magnetic properties, enabling the sense layer to maintain vortex stability at high fields while the reference layer provides a stable reference, thus preventing performance drift and offset shifts
Solution Approach 2:
The sense pinning layer acts as an intermediary between the sense layer and the external environment. By introducing this intermediate layer with specific exchange-bias strength, the patent mediates the interaction between the sense magnetization and high magnetic fields, protecting the vortex configuration from destabilization and maintaining measurement precision under high-field conditions
2Stability of the object's composition
If the sense layer thickness is increased to enhance vortex stability, then the linear response range is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent optimizes the sense layer thickness to a specific range (15-80 nm) to achieve stable vortex configuration. By carefully controlling this geometric parameter, the patent enhances vortex stability without requiring complex structural modifications, thus improving linear response range while maintaining manufacturability
Solution Approach 2:
The patent employs composite magnetic layer structures with specific material compositions. The sense layer is composed of materials that, when combined in specific thickness ratios with the tunnel barrier and reference layers, naturally support stable vortex configurations. This material composition approach achieves vortex stability through inherent magnetic properties rather than complex geometric designs
3Reliability
If exchange-bias strength is increased to improve vortex pinning, then the nominal performance stability is enhanced, but the linear response range is reduced
Solution Approach 1:
The patent applies different exchange-bias strengths to different layers: the reference pinning layer has strong exchange-bias to ensure stable reference magnetization, while the sense pinning layer has optimized exchange-bias strength (2×10⁻⁸ to 4×10⁻⁸ J/cm²) that provides sufficient vortex pinning while allowing adequate response to external fields. This local differentiation resolves the contradiction between stability and response range
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 magnetoresistive element achieves a wide linear response and maintains nominal performance unchanged even after exposure to high magnetic fields, reducing zero-field offset shifts and enhancing sensor accuracy.
Implementation Method 1
a sense pinning layer in contact with the sense layer and pining the sense magnetization by exchange-bias at a second blocking temperature lower that the first blocking temperature
Implementation Method 2
a reference pinning layer in contact with the reference layer and pining the reference magnetization by exchange-bias at a first blocking temperature
Implementation Method 3
The external magnetic field 60 can thus be sensed by measuring a resistance of the magnetoresistive sensor element 2. The resistance depends on the orientation and magnitude of the averaged sense magnetization 230 relative to the reference magnetization 210.
Data Source
AI summary
A magnetoresistive element for a magnetic sensor, the magnetoresistive element including a tunnel barrier layer between a reference layer having a fixed reference magnetization and a sense layer having a free sense magnetization, wherein the sense magnetization includes a stable vortex configuration. The magnetoresistive element further includes a reference pinning layer in contact with the reference layer and pining the reference magnetization by exchange-bias at a first blocking temperature. The magnetoresistive element further includes a sense pinning layer in contact with the sense layer and pining the sense magnetization by exchange-bias at a second blocking temperature lower that the first blocking temperature. Additionally, a method for manufacturing the magnetoresistive element.