Vortex Magnetoresistive Sense Layer Composition for Offset Stability
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Solution Overview
Problem
Vortex-based magnetoresistive sensors suffer from zero-field offset shifts and reduced accuracy when exposed to high magnetic fields, which alter their magnetic configuration and performance.
Innovation Solution
A magnetoresistive element with a ferromagnetic sense layer having a stable vortex configuration and varying ferromagnetic material composition across its thickness, ensuring higher magnetization and exchange strength near the tunnel barrier layer, which maintains sensitivity and reduces zero-field offset shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vortex-based magnetoresistive sensors are exposed to high magnetic fields, then the sensor can be reset or realigned, but the vortex configuration is annihilated or expelled causing zero-field offset shifts that reduce measurement accuracy
Solution Approach 1:
The patent applies local quality by creating a composition gradient within the sense layer where the ferromagnetic material composition varies across the thickness. Specifically, the sense layer has a first portion with a first composition and a second portion with a second composition, creating different magnetic properties in different regions. This gradient structure allows the vortex core to be stabilized in a specific region while maintaining overall vortex configuration, preventing vortex annihilation during high field exposure and reducing zero-field offset shifts.
2Ease of manufacture
If the sense layer has uniform ferromagnetic material composition, then the manufacturing process is simpler, but the sensor suffers from zero-field offset shifts after high field exposure
Solution Approach 1:
The patent implements local quality through a composition gradient in the sense layer, where the ferromagnetic material composition varies across the thickness to create distinct first and second portions with different compositions. This gradient structure stabilizes the vortex configuration and prevents zero-field offset shifts while maintaining manufacturability through controlled deposition processes.
Solution Approach 2:
The patent applies parameter changes by varying the ferromagnetic material composition across the sense layer thickness. The composition gradient creates different magnetic properties (such as magnetization and exchange coupling) in different regions of the sense layer, which stabilizes the vortex configuration and prevents vortex annihilation during high field exposure, thereby reducing zero-field offset shifts.
3Measurement precision
If the ferromagnetic material composition varies across the sense layer thickness, then zero-field offset shifts are reduced, but the device complexity increases
Solution Approach 1:
The patent applies local quality by creating a composition gradient within the sense layer where the ferromagnetic material composition varies across the thickness. Specifically, the sense layer has a first portion with a first composition and a second portion with a second composition, creating different magnetic properties in different regions. This gradient structure allows the vortex core to be stabilized in a specific region while maintaining overall vortex configuration, preventing vortex annihilation during high field exposure and reducing zero-field offset shifts.
Solution Approach 2:
The patent employs composite materials by combining different ferromagnetic material compositions within the sense layer. The sense layer comprises a gradient structure with at least two different ferromagnetic compositions, creating a composite structure that leverages the advantageous properties of each composition to stabilize the vortex configuration and reduce zero-field offset shifts.
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 maintains high sensitivity and nominal performance even after exposure to high magnetic fields, minimizing zero-field offset shifts and ensuring accurate low-field measurements.
Implementation Method 1
The sense magnetization comprises a ferromagnetic material composition and a stable vortex configuration in the absence of an applied magnetic field. The ferromagnetic material composition varies across the thickness of the sense layer in such a way that the sense magnetization and ferromagnetic exchange strength of the sense layer are higher near the tunnel barrier layer than away from the tunnel barrier layer.
Implementation Method 2
The external magnetic field can thus be sensed by measuring a resistance of the magnetoresistive sensor element. The resistance depends on the orientation and magnitude of the averaged sense magnetization relative to the reference magnetization.
Implementation Method 3
a tunnel barrier layer between the reference and sense ferromagnetic layers
Data Source
AI summary
A magnetoresistive element has a tunnel barrier layer included between a ferromagnetic reference layer having a fixed reference magnetization and a ferromagnetic sense layer having a free sense magnetization. The sense magnetization has a ferromagnetic material composition and a stable vortex configuration in the absence of an applied magnetic field. The ferromagnetic material composition varies across the thickness of the sense layer from a composition with higher magnetization near the tunnel barrier layer to a composition with lower magnetization away from the tunnel barrier layer, such that the sense magnetization and ferromagnetic exchange strength of the sense layer are higher near the tunnel barrier layer than away from the tunnel barrier layer.