Magnetoresistive Element with PMA Vortex Sense Layer for Out-of-Plane Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetoresistive elements face challenges in achieving high out-of-plane sensitivity due to difficulties in fabrication processes, particularly with thick sense layers, which can lead to reduced element density and increased complexity.
Innovation Solution
A magnetoresistive element with a sense layer having a vortex configuration and perpendicular magnetic anisotropy, allowing for stable sense magnetization under external fields, and a tunnel barrier layer, enabling high out-of-plane sensitivity without the need for thick sense layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thick sense layers (>100 nm) are used to achieve high out-of-plane sensitivity, then sensitivity is improved, but fabrication complexity increases and element density decreases
Solution Approach 1:
The invention changes the magnetic anisotropy parameter from in-plane to perpendicular magnetic anisotropy (PMA) in the sense layer. This parameter change allows the sense layer to maintain stable magnetization and achieve high out-of-plane sensitivity with a reduced thickness of 5-50 nm, avoiding the fabrication complexities associated with thick layers while preserving measurement precision
Solution Approach 2:
The invention introduces perpendicular magnetic anisotropy (out-of-plane dimension) to control the sense magnetization direction, rather than relying on in-plane magnetization. This dimensional change in magnetic anisotropy enables the use of thinner sense layers while maintaining or improving out-of-plane sensitivity, thereby reducing fabrication complexity and increasing element density
2Measurement precision
If thick sense layers (>100 nm) are used to achieve high out-of-plane sensitivity, then sensitivity is improved, but element density decreases
Solution Approach 1:
By changing the magnetic anisotropy parameter to perpendicular PMA, the invention enables high sensitivity with thin sense layers (5-50 nm), which directly increases the number of elements that can be packed into a given area, thereby improving element density while maintaining measurement precision
Solution Approach 2:
The introduction of perpendicular magnetic anisotropy allows the sense layer to respond to out-of-plane fields efficiently with reduced thickness, enabling higher element density without sacrificing sensitivity. The vortex core magnetization along the out-of-plane axis provides the necessary response to external fields despite the reduced layer thickness
3Ease of manufacture
If sense layer thickness is reduced to simplify fabrication, then fabrication complexity decreases, but out-of-plane sensitivity deteriorates
Solution Approach 1:
The invention changes the magnetic anisotropy parameter to perpendicular PMA, which compensates for the reduced sense layer thickness. This parameter change ensures that even thin layers (5-50 nm) maintain stable magnetization and achieve high out-of-plane sensitivity, thus improving fabrication ease without deteriorating measurement precision
Solution Approach 2:
The sense layer is designed as a composite structure with specific ferromagnetic materials (CoFeB, CoFe, NiFe) and controlled thickness, combined with perpendicular magnetic anisotropy engineering. This composite approach enables thin layers to achieve both fabrication ease and high sensitivity through optimized material composition and magnetic properties
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 achieves high out-of-plane sensitivity with a compact sensor layout, maintaining sensitivity levels comparable to thicker sense layers while simplifying the fabrication process and increasing sensor density.
Implementation Method 1
For the magnetoresistive element to sense an external magnetic field with high out-of-plane sensitivity, it must have a high tunnel magnetoresistance (TMR) value
Implementation Method 2
the sense layer has a perpendicular magnetic anisotropy field HMPA that is greater than 1 kOe (79.6×103 A/m)
Implementation Method 3
The sense magnetization comprising a vortex configuration in the absence of an external magnetic field. The vortex configuration is substantially parallel to the plane of the sense layer and has a vortex core magnetization direction along an out-of-plane axis
Data Source
AI summary
The present disclosure concerns a magnetoresistive element comprising a reference layer having a reference magnetization oriented out-of-plane; a sense layer having a sense magnetization comprising a vortex configuration stable under the presence of an external magnetic field and reversibly movable in a direction out-of-plane relative to the reference magnetization when the external magnetic field varies in a direction out-of-plane; and a tunnel barrier layer between the reference layer and the sense layer. The sense layer has a thickness smaller than 200 nm. The sense layer comprises a ferromagnetic material configured such that the sense magnetization is between 300 and 1400 emu/cm3 and such that the sense layer has a perpendicular magnetic anisotropy field that is greater than 1 kOe (79.6×103 A/m). The present disclosure further concerns a magnetoresistive sensor comprising a plurality of the magnetoresistive element.