Vortex Magnetoresistive Element With Graded Sense Layer Stability
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Solution Overview
Problem
Vortex-based magnetoresistive sensors experience zero-field offset shifts and reduced accuracy when exposed to high magnetic fields, affecting their performance in low-field measurements.
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 near the tunnel barrier layer and lower magnetization away from it, which maintains sensitivity and reduces zero-field offset-shifts even under high magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vortex-based magnetoresistive sensor is exposed to high magnetic fields, then the sensor can be used for reliability testing and high-field applications, 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 higher magnetization near the tunnel barrier layer and lower magnetization away from it, which creates different local magnetic properties that stabilize the vortex configuration against high-field annihilation while maintaining low-field measurement accuracy
Solution Approach 2:
The patent changes the magnetic parameters of the sense layer by varying the ferromagnetic material composition across the layer thickness. This composition gradient results in a position-dependent magnetization profile, where the magnetization magnitude and exchange strength vary continuously from the tunnel barrier interface toward the sense layer exterior, thereby tuning the vortex stability against high magnetic fields
2Ease of manufacture
If the sense layer has uniform ferromagnetic material composition, then the manufacturing process is simpler, but the vortex configuration is more susceptible to annihilation under high magnetic fields
Solution Approach 1:
The patent implements local quality by introducing a composition gradient in the ferromagnetic material across the sense layer thickness. This creates spatially varying magnetic properties, with higher magnetization near the tunnel barrier and lower magnetization toward the exterior, which enhances vortex stability without significantly complicating the manufacturing process
Solution Approach 2:
The patent uses composite material structure by combining ferromagnetic materials with different compositions within the same sense layer. The sense layer effectively becomes a composite structure with a gradient of magnetic properties, achieving superior vortex stability while maintaining compatibility with standard fabrication processes
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 without significant changes when exposed to high magnetic fields, reducing zero-field offset-shifts and enhancing accuracy in low-field measurements.
Implementation Method 1
a tunnel barrier layer (22) included between a ferromagnetic reference layer (21) having a fixed reference magnetization (210) and a ferromagnetic sense layer (23) having a free sense magnetization (230)
Implementation Method 2
The sense magnetization (230) comprises a ferromagnetic material composition and a stable vortex configuration in the absence of an applied magnetic field
Implementation Method 3
In the vortex configuration, the magnetization curls in a circular path along the edge of the sense layer and around a core reversibly movable in accordance with the external magnetic field
Implementation Method 4
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
Data Source
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AI summary
A magnetoresistive element (2) comprises a tunnel barrier layer (22) included between a ferromagnetic reference layer (21) having a fixed reference magnetization (210) and a ferromagnetic sense layer (23) having a free sense magnetization (230). The sense magnetization (230) 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 (23) from a composition with higher magnetization near the tunnel barrier layer (22) to a composition with lower magnetization away from the tunnel barrier layer (22), such that the sense magnetization (230) and ferromagnetic exchange strength of the sense layer (23) are higher near the tunnel barrier layer (22) than away from the tunnel barrier layer (22).