Magnetic Element Vortex Core Indentation for Offset Reduction
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Solution Overview
Problem
Current magnetic sensors face a non-reproducible offset in magnetization distribution due to vortex core path differences when subjected to external magnetic fields, leading to a reduced measurement range and performance limitations.
Innovation Solution
A magnetic tunnel junction with a ferromagnetic layer having an elliptical shape and an indentation, where the vortex core nucleates at the indentation, ensuring identical displacement paths regardless of the magnetic field direction, thereby maintaining consistent magnetization distribution and increasing the measurement range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional ferromagnetic layer without indentation is used, then the vortex core can move freely under external magnetic fields, but the vortex core path becomes non-reproducible leading to offset in magnetization distribution
Solution Approach 1:
An indentation is introduced at a specific location on the ferromagnetic layer, creating an asymmetric geometric feature that serves as a predetermined nucleation site for the vortex core. This asymmetric structure ensures that the vortex core consistently forms at the indentation location regardless of the direction of the applied magnetic field, thereby making the vortex core path reproducible and eliminating offset in magnetization distribution.
2Adaptability or versatility
If the measurement range is expanded, then more magnetic field conditions can be measured, but the non-reproducible offset limits the effective measurement range
Solution Approach 1:
The indentation creates a preferred nucleation site that ensures consistent vortex core formation across different magnetic field conditions. This allows the magnetic element to maintain reproducible magnetization distribution over an expanded measurement range, as the vortex core consistently returns to the indentation location during remanent state regardless of field history.
3Ease of manufacture
If the ferromagnetic layer has a simple circular shape, then the manufacturing is easier, but the vortex core path varies depending on field direction reducing measurement accuracy
Solution Approach 1:
While maintaining overall circular geometry for ease of manufacture, a small indentation is introduced as a minor asymmetric feature. This indentation serves as a vortex core nucleation site without significantly complicating the fabrication process, while effectively ensuring consistent vortex core path and magnetization distribution.
Solution Approach 2:
The indentation introduces a localized geometric feature with different properties from the rest of the circular ferromagnetic layer. This local modification creates a preferred nucleation site that controls vortex core formation, while the majority of the layer maintains its simple circular shape for easy manufacturing.
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 solution provides improved reproducibility and expanded measurement range by controlling the vortex core path within the ferromagnetic layer, minimizing offset and enhancing sensor performance.
Implementation Method 1
a magnetic tunnel junction (502) including a tunnel barrier layer (503) sandwiched between a first ferromagnetic layer (501) having a first magnetization (510) and a second ferromagnetic layer (504) having a second magnetization (520)
Implementation Method 2
Applying the external magnetic field H x along the easy axis of the first ferromagnetic layer 21 (along the x direction in Fig. 1), causes the vortex core 211 to move in a direction being substantially perpendicular to the easy axis of the first ferromagnetic layer 21
Data Source
Figure 1(a)~2
Figure 3~4
Figure 5~6
AI summary
Magnetic element (10) comprising: a magnetic tunnel junction element (2) including a tunnel barrier layer (22) sandwiched between a first ferromagnetic layer (21) having a first magnetization (210) and a second ferromagnetic layer (23) having a second magnetization (230); a field device (40) configured to generate an external magnetic field (42) adapted for varying the orientation of the first magnetization (210) while the orientation of the second magnetization (230) remain unchanged; the first ferromagnetic layer (21) being configured such that the first magnetization (210) comprises a stable magnetization vortex configuration; the first ferromagnetic layer (21) being further configured to comprise an indentation (50) such that a vortex core (211) of the magnetization vortex, upon vortex nucleation or renucleation, is located in the vicinity of the indentation (50) and such that applying the external magnetic field in a first direction moves the vortex core along a first path, the first magnetization rotating around the vortex core in a counterclockwise direction in the plane of the first ferromagnetic layer and applying the external magnetic field in a second direction, opposed to the first direction, moves the vortex core along a second path, the first magnetization rotating around the vortex core in a clockwise direction in the plane of the first ferromagnetic layer, wherein both the first and second path of the vortex core are substantially identical and lead the vortex core away from the indentation.