Magnetic Sensor In-Plane Anisotropy Control Layer
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Solution Overview
Problem
Magnetic sensors using magnetic impedance effect elements face challenges in generating in-plane magnetic anisotropy without a control layer, which affects their sensitivity and accuracy in detecting magnetic fields.
Innovation Solution
A magnetic sensor design incorporating a thin film magnet with in-plane magnetic anisotropy, a sensitive part with uniaxial anisotropy, and a control layer made of Cr, Mo, or W alloys, along with an adhesive layer and demagnetizing field suppressing layers, to enhance magnetic flux guidance and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a thin film magnet is formed without a control layer, then the structure is simpler, but in-plane magnetic anisotropy cannot be generated
Solution Approach 1:
A control layer made of Cr, Mo, or W is introduced as an intermediary between the substrate and the hard magnetic film. This control layer mediates the crystal growth process, causing the hard magnetic film to form with in-plane magnetic anisotropy through epitaxial growth on the control layer's crystal structure.
Solution Approach 2:
The control layer changes the crystal growth parameters of the hard magnetic film. By providing a specific crystal structure (bcc for Cr/Mo/W), it directs the hard magnetic film to grow with c-axis orientation in the in-plane direction, thereby generating in-plane magnetic anisotropy instead of the conventional out-of-plane anisotropy.
2Measurement precision
If a control layer is added to generate in-plane magnetic anisotropy, then magnetic sensor sensitivity is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The control layer enables parameter changes in the hard magnetic film's crystal structure, transforming it to have in-plane anisotropy. This single layer addition modifies the growth parameters of subsequent layers, achieving sensitivity improvement without requiring multiple complex process steps.
3Manufacturing precision
If crystal growth is conducted on the bcc structure of the control layer, then c-axis of hcp structure becomes oriented in-plane, but control layer material selection is limited
Solution Approach 1:
The invention changes the material parameter of the control layer to specific elements (Cr, Mo, W) that possess bcc crystal structure. This parameter change enables the desired c-axis in-plane orientation of the hard magnetic film while maintaining a limited but effective material selection.
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 enables improved magnetic anisotropy control, increased sensitivity, and effective bias magnetic field application, reducing the need for external coils and enhancing power efficiency and sensor stability.
Implementation Method 1
a thin film magnet that is configured with a hard magnetic material and has magnetic anisotropy in an in-plane direction
Implementation Method 2
in the hard magnetic material, crystal growth is conducted on the bcc structure of the control layer to cause a c-axis of the hcp structure to be oriented in-plane
Implementation Method 3
a sensitive element that is configured with a soft magnetic material and is disposed to face the thin film magnet, the sensitive element having a longitudinal direction in which a magnetic flux generated by the thin film magnet passes through
Implementation Method 4
magnetic sensor using the magnetic impedance effect element
Implementation Method 5
an adhesive layer is provided between the substrate and the control layer, the adhesive layer improving adhesiveness of the control layer to the substrate
Data Source
AI summary
A magnetic sensor 1 is provided with: a thin film magnet 20 configured with a hard magnetic material and having magnetic anisotropy in an in-plane direction; a sensitive part 30 including a sensitive element 31 configured with a soft magnetic material and disposed to face the thin film magnet 30, the sensitive element 31 having a longitudinal direction in which a magnetic flux generated by the thin film magnet 20 passes through and a short direction, having uniaxial magnetic anisotropy in a direction crossing the longitudinal direction, and sensing a change in a magnetic field; and a control layer 102 disposed on a side of the thin film magnet 20 opposite to a side of the thin film magnet 20 on which the sensitive element 31 is provided, the control layer 102 controlling the magnetic anisotropy of the thin film magnet 20 to be directed in the in-plane direction.