L10-Ordered Alloy SOT Device for Perpendicular Magnetization Switching
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Solution Overview
Problem
Existing spin-orbit torque (SOT) devices require multiple layers for magnetization switching, which limits their efficiency and thermal stability, and struggle with achieving perpendicular magnetization switching necessary for high-density storage.
Innovation Solution
A SOT device utilizing a single L10-ordered magnetic alloy layer, such as iron-platinum (FePt) or cobalt-platinum (CoPt), with strong spin-orbit coupling, allows for current-induced perpendicular magnetization switching, eliminating the need for bilayers and enhancing charge-to-spin conversion efficiency and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional heavy metal/ferromagnet bilayers are used for SOT devices, then the device structure is established, but the spin-torque efficiency is limited due to interface effects and spin relaxation
Solution Approach 1:
The patent merges the spin Hall material and ferromagnet into a single L10-ordered alloy layer that simultaneously provides both the spin Hall effect and ferromagnetic properties. This eliminates the interface between two separate layers, removing the source of spin relaxation and improving spin-torque efficiency while simplifying the device structure from a bilayer to a monolayer configuration
Solution Approach 2:
The patent employs a composite L10-ordered alloy material (such as CoPt, FePt, or CoPd) that combines heavy metal atoms with ferromagnetic atoms in a specific ordered crystal structure. This composite material inherently possesses both strong spin-orbit coupling for high spin Hall angle and ferromagnetic ordering for magnetization switching, achieving high spin-torque efficiency within a single layer
2Reliability
If bilayer structures are used for magnetization switching, then magnetization manipulation is achieved, but thermal stability is reduced
Solution Approach 1:
By combining the spin Hall functionality and ferromagnetic storage functionality into a single L10-ordered alloy layer, the patent eliminates the interface between layers that would otherwise be a pathway for thermal energy transfer and a source of instability. The single layer structure reduces thermal pathways and improves thermal stability while maintaining magnetization switching capability
Solution Approach 2:
The patent changes the material parameter from conventional separate HM/FM layers to a single L10-ordered alloy with high magnetocrystalline anisotropy energy. This parameter change in the material composition and crystal structure inherently provides both the spin Hall effect and enhanced thermal stability through the ordered alloy structure's resistance to thermal fluctuations
3Adaptability or versatility
If conventional SOT devices are designed, then in-plane magnetization switching is achieved, but perpendicular magnetization switching necessary for high-density storage cannot be realized
Solution Approach 1:
The patent uses a composite L10-ordered alloy material that inherently possesses perpendicular magnetic anisotropy due to its tetragonal crystal structure and spin-orbit coupling. This material property enables perpendicular magnetization switching without requiring complex multilayer structures or external magnetic fields, achieving high-density storage capability in a manufacturable single layer device
Solution Approach 2:
The patent changes the magnetic anisotropy parameter from in-plane to perpendicular by selecting L10-ordered alloy materials with strong spin-orbit coupling and specific crystal orientations. This parameter change in the material's magnetic properties enables perpendicular magnetization switching, which is essential for high-density storage applications, while maintaining the simplicity of a single layer structure
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 single L10-ordered alloy layer SOT device achieves higher spin torque efficiency, thermal stability, and reduced fabrication complexity, enabling efficient perpendicular magnetization switching and multi-level resistance states without external magnetic fields.
Implementation Method 1
The SOT originates from the large spin orbit coupling in these alloys
Implementation Method 2
current-induced SOT in a L10-ordered magnetic alloy layer to change magnetization direction
Implementation Method 3
to achieve perpendicular magnetocrystalline anisotropy (PMA)
Implementation Method 4
which may apply a biased field through antiferromagnet exchange coupling, to permit magnetization switching in the absent of an external magnetic field
Data Source
AI summary
In one embodiment, a SOT device provides current-induced perpendicular magnetization switching in a single magnetic layer, such as a L10-ordered magnetic alloy layer of FePt alloy, CoPt alloy, FePd alloy or another atomically layered magnetic alloy. The SOT may originate from the large spin orbit coupling in these alloys. Depending on the implementation, the SOT device may take the form of a SOT-MRAM, a spin memristor, a current-assisted magnetic recording media, or other type of device.