Magnetic Sensor MR Element Edge Thickness Profile
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Solution Overview
Problem
Magnetic sensors using magnetoresistive elements face nonlinearity in detection signals due to demagnetizing fields, which limits the range of magnetic field detection and increases errors in signal processing, as the strength of demagnetizing fields varies between the edges and midsection of the magnetic layer.
Innovation Solution
The magnetic sensor design includes a magnetoresistive element with a magnetic layer having a thickness and inclination angle that varies across its surface, reducing the concentration of magnetic charges at the edges by making the thickness smaller at the edges compared to the midsection and adjusting the inclination angle, thereby expanding the range where the detection signal changes linearly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the magnetic layer has uniform thickness across the surface, then the manufacturing process is simple, but the detection signal becomes nonlinear due to varying demagnetizing field strength at edges versus midsection
Solution Approach 1:
The magnetic layer is designed with non-uniform thickness where the thickness is smaller at the edges and larger at the midsection. This local variation in thickness compensates for the demagnetizing field strength differences across the magnetic layer, making the detection signal more linear while maintaining manufacturing feasibility through standard thin-film deposition techniques.
2Object-generated harmful factors
If the thickness of the magnetic layer is reduced at the edges, then the concentration of magnetic charges at the edges is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The thickness parameter of the magnetic layer is deliberately varied across the surface, with specific control to reduce thickness at edges and increase it at the midsection. This parameter change is implemented through controlled thin-film deposition processes, achieving the desired thickness profile to reduce magnetic charge concentration while maintaining manufacturability.
3Adaptability or versatility
If the magnetic layer thickness varies across the surface, then the range of linear detection signal expansion is increased, but the device complexity increases
Solution Approach 1:
The magnetic layer employs local quality variations in thickness to expand the linear detection range. The thickness is specifically controlled to be smaller at edges and larger at the midsection, creating a tailored magnetic charge distribution that enhances detection capability without requiring complex multi-layer structures or additional components.
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
This design reduces the nonlinearity of the detection signal, allowing for a broader range of magnetic field detection and improving signal processing accuracy by minimizing the difference in demagnetizing fields across the magnetic layer.
Implementation Method 1
a magnetoresistive element whose resistance changes with an external magnetic field
Implementation Method 2
a magnetic layer having a magnetization whose direction is variable depending on the direction of an applied magnetic field
Implementation Method 3
Magnetic anisotropy is often controlled by using magnetic shape anisotropy. Magnetic shape anisotropy can be set by patterning the magnetoresistive element to a shape that is long in one direction
Implementation Method 4
a demagnetizing field in a direction opposite to that of the external magnetic field occurs in the magnetic layer due to magnetic charges occurring at the edges of the magnetic layer
Data Source
AI summary
A magnetic sensor includes an MR element. The MR element includes a free layer. The free layer has a first surface having a shape that is long in one direction and a second surface located opposite the first surface, and has a thickness that is a dimension in a direction perpendicular to the first surface. The first surface has a first edge and a second edge located at both lateral ends of the first surface. In a given cross section, the thickness at the first edge is smaller than the thickness at a predetermined point on the first surface between the first edge and the second edge.