Multilayer Magnetic Device with Interfacial Anisotropy
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Solution Overview
Problem
Current magnetic materials do not combine high longitudinal resistivity, high Hall resistivity, and strong perpendicular magnetic susceptibility, limiting their effectiveness in magnetic field sensors and memories.
Innovation Solution
A multilayer magnetic device with alternating magnetic metal layers and oxide, hydride, or nitride layers, where the magnetic layers are thin and the oxide, hydride, or nitride layers are used to create interfacial magnetic anisotropy, enhancing perpendicular magnetic anisotropy and resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional magnetic materials are used, then the device structure is simple, but the material cannot simultaneously achieve high longitudinal resistivity, high Hall resistivity, and strong perpendicular magnetic susceptibility
Solution Approach 1:
The patent employs composite multilayer structures alternating magnetic metal layers (Fe, Co, Ni or their alloys) with non-magnetic spacer layers (oxides, hydrides, or nitrides). This composite approach enables the system to simultaneously achieve high longitudinal resistivity (ρxx ≥ 100 μΩcm), high Hall resistivity (|ρxy| ≥ 10 μΩcm), and strong perpendicular magnetic susceptibility through interfacial magnetic anisotropy, which cannot be obtained with single conventional magnetic materials.
Solution Approach 2:
The patent transitions from studying magnetization primarily in the plane to exploiting perpendicular magnetization out-of-plane through interfacial magnetic anisotropy at the magnetic metal/oxide interfaces. This dimensional change enables access to new magnetic properties and higher performance metrics that were not available in conventional planar magnetic materials.
2Reliability
If thin magnetic layers are used to increase resistivity, then longitudinal resistivity and Hall resistivity improve, but the magnetic signal strength may decrease
Solution Approach 1:
The multilayer composite structure compensates for the reduced magnetic moment in thin layers by providing multiple interfaces that generate perpendicular magnetic anisotropy. The cumulative effect of multiple magnetic layers with interfacial anisotropy maintains strong magnetic susceptibility while preserving the high resistivity benefits of thin individual layers.
Solution Approach 2:
The magnetic structure is segmented into multiple thin magnetic metal layers separated by non-magnetic spacer layers. Each interface between magnetic and non-magnetic layers contributes to the overall perpendicular magnetic anisotropy, allowing the system to achieve strong magnetic response despite the thinness of individual magnetic layers.
3Reliability
If oxide layers are introduced to create interfacial magnetic anisotropy, then perpendicular magnetic susceptibility improves, but the device structure and manufacturing process become more complex
Solution Approach 1:
The oxide layers are formed by performing oxidation as a preliminary action during the sputtering process. By introducing oxygen into the sputtering atmosphere, the oxide layers are created in-situ during deposition, which simplifies the overall manufacturing process compared to separate oxidation steps, and enables precise control of oxide thickness and 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 solution achieves high sensitivity to magnetic fields, with a strong Hall coefficient and longitudinal resistivity, suitable for magnetic field sensors, memories, and logic gates, while maintaining stability against external disturbances.
Implementation Method 1
an interfacial magnetic anisotropy perpendicular to the plane of the layers at the M/O and O/M interfaces exists for a temperature range equal to or greater than ambient temperature, capable of orienting the magnetization of the M layers substantially perpendicular to the plane of the layers
Implementation Method 2
magnetic devices allowing the detection of magnetic fields based on the measurement of the Extraordinary Hall Effect. The Extraordinary Hall Effect exists exclusively in ferromagnetic materials and results from the diffusion of electrons by spin-orbit interaction with the magnetic moments of the ferromagnetic material
Implementation Method 3
The Ordinary Hall Effect exists in metallic materials or doped semiconductors, and is due to the Lorentz force acting on electrons under the effect of a magnetic field
Data Source
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AI summary
This multilayer magnetic device comprises, on a substrate, alternating magnetic metallic layers M and oxide, hydride or nitride layers O. The number of M layers is at least equal to two. The M layers are continuous, have a thickness of less than or equal to 5 nanometres and their magnetization would be parallel to the plane of the layers in the absence of the O layers. Moreover, there is, for a temperature range equal to or greater than ambient temperature, an interfacial magnetic anisotropy perpendicular to the plane of the layers at the M/O and O/M interfaces, capable of orienting the magnetization of the M layers substantially perpendicular to the plane of the layers.