Three-Layer Magnetic Element for High Sensitivity Hall Sensors
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Solution Overview
Problem
Current magnetic materials lack the combination of high longitudinal resistivity, high Hall resistivity, and high perpendicular magnetic susceptibility necessary for effective magnetic field sensing and memory applications, particularly in devices utilizing the extraordinary Hall effect.
Innovation Solution
A three-layer magnetic element structure comprising a substrate with an oxide, hydride, or nitride layer, a thin magnetic metal layer, and an additional oxide or non-ferromagnetic metal layer, which achieves high perpendicular magnetic anisotropy and longitudinal resistivity through strain and interfacial electronic hybridization effects, enabling sensitive magnetic field detection and stable magnetization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional magnetic materials are used, then the device structure is simple, but the combination of high longitudinal resistivity, high Hall resistivity, and high perpendicular magnetic susceptibility cannot be achieved
Solution Approach 1:
The patent employs a composite multi-layer structure consisting of ferromagnetic layers (Co, CoFeB, CoFe), non-magnetic metal layers (Pt, Pd, Ru, Rh, Ir), and oxide layers (MgO, Al2O3, SiO2). This composite structure combines the advantages of different materials: ferromagnetic layers provide high magnetization, heavy metal layers induce perpendicular magnetic anisotropy through spin-orbit coupling, and oxide layers provide high longitudinal resistivity and structural stability, achieving the required combination of high longitudinal resistivity, high Hall resistivity, and high perpendicular magnetic susceptibility
Solution Approach 2:
The magnetic element is segmented into multiple functional layers with specific thicknesses (e.g., ferromagnetic layer: 1-5 nm, heavy metal layer: 2-10 nm, oxide layer: 1-3 nm). Each layer performs a specific function: the ferromagnetic layer stores magnetic information, the heavy metal layer induces perpendicular anisotropy, and the oxide layer provides electrical insulation and structural support. This segmentation allows optimization of each layer's properties to achieve overall high sensing performance
2Reliability
If the magnetic layer thickness is increased to improve signal strength, then the voltage response increases, but the current required increases to values that cause irreversible structural modifications
Solution Approach 1:
The patent introduces oxide layers (MgO, Al2O3, SiO2) with high electrical resistivity at specific locations within the magnetic element structure. These oxide layers are positioned between the ferromagnetic layer and heavy metal layer, or as capping layers, to locally increase longitudinal resistivity. This local quality enhancement allows the device to maintain sufficient voltage response while limiting current density to values below the electromigration threshold, preventing irreversible structural modifications
3Reliability
If materials with high spin-orbit diffusion are used to maximize Hall resistivity, then the extraordinary Hall effect increases, but the concentration must be limited to preserve magnetic properties
Solution Approach 1:
The patent uses composite structures where heavy metal layers (Pt, Pd, Ru, Rh, Ir) with high spin-orbit diffusion coefficients are combined with ferromagnetic layers (Co, CoFeB, CoFe) and oxide layers. The heavy metal layers are deposited in controlled thicknesses (2-10 nm) to maximize spin-orbit coupling effects and enhance the extraordinary Hall effect, while the ferromagnetic layers maintain their magnetic properties. The oxide layers provide structural stability and electrical insulation, allowing the system to achieve high Hall resistivity without compromising the ferromagnetic alloy composition
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 structure enhances magnetic field sensitivity and stability, allowing for efficient detection of magnetic fields and reliable magnetization orientation, suitable for applications in magnetic field sensors, memories, and logic gates.
Implementation Method 1
The extraordinary Hall effect occurs to a limited extent in ferromagnetic materials and is the result of diffusion of electrons due to spin-orbit interaction with the magnetic moments of the ferromagnetic material.
Implementation Method 2
which achieves high perpendicular magnetic anisotropy and longitudinal resistivity through strain and interfacial electronic hybridization effects
Implementation Method 3
or by measuring the magnetoresistance or the Kerr effect or the Faraday magneto-optical effect
Implementation Method 4
or by measuring the magnetoresistance or the Kerr effect or the Faraday magneto-optical effect
Data Source
AI summary
A three-layer magnetic element comprises, on a substrate, a first oxide, hydride or nitride layer O having a metal magnetic layer M mounted thereon, the latter having either a second oxide, hydride or nitride layer O′, or a non-ferromagnetic metal layer M′ mounted thereon. Layer M is continuous, has a thickness of 1 to 5 nm and the magnetization thereof is parallel to the layer plane in the absence of layers O and O′. There is, for a range of temperature equal to or greater than ambient temperature, interfacial magnetic anisotropy perpendicular to the layer plane on interfaces O/M and M/O′ that is capable of decreasing the effective demagnetizing field of layer M or orienting the magnetization of layer M in a manner substantially perpendicular to the layer plane.