Spin-Orbit Torque Wiring Structure for Low-Current Magnetization Reversal
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Solution Overview
Problem
Existing magnetoresistance effect elements face challenges in achieving low reversal current density for magnetization reversal while maintaining high integration and low energy consumption, particularly due to the use of heavy metal materials with high electrical resistivity and lattice mismatch issues.
Innovation Solution
A spin current magnetization rotational element is designed with a spin-orbit torque wiring that combines a spin conduction layer and a spin generation layer, utilizing both the spin Hall effect and interface Rashba effect, with specific material and thickness ratios to reduce power consumption and lattice mismatch, allowing for efficient magnetization reversal using a pure spin current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heavy metal materials are used for spin-orbit torque wiring to generate spin Hall effect, then magnetization reversal can be achieved, but electrical resistivity is high causing power consumption increase
Solution Approach 1:
The patent uses a composite structure consisting of a spin generation layer (heavy metal material with high spin Hall angle) and a spin conduction layer (low resistivity material). This composite wiring combines the spin Hall effect generation capability of heavy metals with the low electrical resistance of conductive materials, thereby reducing overall power consumption while maintaining magnetization reversal capability
Solution Approach 2:
The spin conduction layer acts as an intermediary between the spin generation layer and the ferromagnetic layer. It receives spin current from the heavy metal layer and efficiently transports it to the ferromagnetic layer, reducing energy loss during spin current transmission and lowering the overall reversal current density
2Reliability
If heavy metal materials are used for spin-orbit torque wiring, then spin Hall effect can be generated, but lattice mismatch with ferromagnetic layer occurs
Solution Approach 1:
The spin conduction layer serves as an intermediary layer between the spin generation layer and the ferromagnetic layer. This intermediate layer is specifically selected to have good lattice matching with the ferromagnetic layer, thereby reducing lattice mismatch and interface defects while still allowing effective spin current transmission from the heavy metal layer
3Reliability
If spin-orbit torque wiring with high electrical resistivity is used, then spin Hall effect can be utilized, but reversal current density remains high
Solution Approach 1:
The composite wiring structure combines a spin generation layer with high spin Hall angle and a spin conduction layer with low electrical resistivity. This composite design separates the spin Hall effect generation function from the spin current transport function, optimizing each for its specific role and achieving low reversal current density
Solution Approach 2:
The patent optimizes the thickness parameters of both the spin generation layer and spin conduction layer to achieve the best balance between spin Hall effect generation and electrical resistance. By carefully controlling these dimensional parameters, the reversal current density is minimized while maintaining effective magnetization reversal
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 effectively reduces power consumption and reversal current density, enabling high integration and stable magnetization reversal through the use of a low-resistance spin-orbit torque wiring that incorporates materials with optimized film thickness ratios and lattice matching.
Implementation Method 1
A pure spin current generated by a spin Hall effect induces a spin-orbit torque (SOT) and the SOT causes magnetization reversal to occur
Implementation Method 2
a spin conduction layer joined to the first ferromagnetic metal layer and configured to conduct a spin current generated by the spin-orbit torque wiring to the first ferromagnetic metal layer
Implementation Method 3
it is required to effectively produce both the spin Hall effect and an interface Rashba effect that occurs at an interface between different materials
Data Source
AI summary
This spin current magnetization rotational element includes a first ferromagnetic metal layer for a magnetization direction to be changed, and a spin-orbit torque wiring extending in a second direction intersecting a first direction which is an orthogonal direction to a surface of the first ferromagnetic metal layer and configured to be joined to the first ferromagnetic metal layer, wherein the spin-orbit torque wiring has a structure in which a spin conduction layer joined to the first ferromagnetic metal layer and a spin generation layer joined to the spin conduction layer on a surface on a side opposite to the first ferromagnetic metal layer are laminated.