Writable Magnetic Element Spin-Orbit Magnetization Control
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Solution Overview
Problem
Current magnetic random access memory (MRAM) and logic devices face challenges in integrating spin transfer torque (STT) technology due to high power dissipation and complexity in stack structuring, as well as the intrinsic link between writing and reading processes, which complicates independent optimization of these functions.
Innovation Solution
A writable magnetic element with a central magnetic layer sandwiched between non-magnetic outer layers, where a write current is passed parallel to the plane of the central layer, generating a spin-orbit magnetic field to manipulate magnetization without an external magnetic field, allowing for independent optimization of writing and reading processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high density current is injected perpendicular to the plane of magnetic layers to flip magnetization by spin transfer torque, then magnetization reversal is achieved, but power consumption increases and the stack structure becomes complex
Solution Approach 1:
The patent changes the current injection direction from perpendicular to parallel with the plane of the magnetic layer. This dimensional change enables the use of spin-orbit coupling effects at the interface between the magnetic layer and adjacent non-magnetic layers, achieving magnetization reversal through a different physical mechanism that requires lower power consumption
Solution Approach 2:
The patent modifies the physical parameters of the magnetic stack by introducing specific non-magnetic layers with particular properties (such as Ru, Rh, Ir) adjacent to the magnetic layer. These parameter changes enable enhanced spin-orbit coupling and interfacial Dzyaloshinskii-Moriya interaction, allowing efficient magnetization control with reduced current density
2Reliability
If multiple magnetic layers and antiferromagnetic materials are added to stabilize magnetization and increase spin transfer torque, then magnetization control is improved, but device complexity increases
Solution Approach 1:
The patent introduces asymmetric structures at the interfaces between magnetic and non-magnetic layers, creating unbalanced spin-orbit coupling effects. This asymmetry generates effective magnetic fields that enable precise magnetization control without requiring symmetric multi-layer configurations or additional antiferromagnetic stabilization layers
Solution Approach 2:
The patent replaces the traditional mechanical approach of adding multiple layers and antiferromagnetic materials with a field-based approach using spin-orbit coupling and interfacial magnetic interactions. This substitution achieves magnetization control through electromagnetic effects rather than physical layer stacking, reducing structural complexity
3Device complexity
If the same stack structure is used for both writing and reading operations, then device simplicity is maintained, but independent optimization of writing and reading processes is prevented
Solution Approach 1:
The patent creates a universal magnetic layer structure that can be controlled by both spin transfer torque (for writing) and magnetoresistance effects (for reading). The same magnetic layer serves dual functions: its magnetization direction is manipulated by spin-polarized current for writing, while its resistance state is detected for reading, enabling independent optimization of both operations through the same structural element
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
This solution reduces power consumption and decouples writing and reading processes, enabling more efficient and complex stack structuring, while maintaining effective magnetization control without the need for external magnetic fields.
Implementation Method 1
The write current is passed through the second outer layer and the central layer in a direction of current parallel to the plane of the central layer... to generate in the central layer an effective magnetic field (or spin-orbit field)
Data Source
Figure 1a~1g
Figure 2a~3b
Figure 4
AI summary
The invention relates to a writable magnetic element comprising a film multilayer containing a write magnetic film, characterized in that the multilayer comprises a central film (13, 53, 100) made of at least one magnetic material having a magnetization with a magnetization direction parallel to the plane of the central film (13, 53, 100), the latter being sandwiched between a first external film (12, 52, 101) and a second external film (14, 54, 102) both made of non-magnetic materials, the first external film (12, 52, 101) comprising a first non-magnetic material and the second external film (14, 54, 102) comprising a second non-magnetic material that is different from the first non-magnetic material, at least the second non-magnetic material being electrically conductive, and in that the element comprises a device for making a write current flow through the second external film (14, 54, 102) and the central film (13, 53, 100) in a flow direction parallel to the plane of the central film (13, 53, 100) and at an angle a of 90o ± 60o, especially of 90o ± 30o and more particularly 90o ± 15o to said magnetization direction, so as to generate a useful magnetic field in the central film (13, 53, 100), this current being made to flow either in a first direction, or in a second direction opposite to the first direction, so as to orient the magnetization direction in a first magnetization direction or in a second magnetization direction opposite to the first magnetization direction.