Asymmetric Lamination Structure for Spin Current Magnetization
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Solution Overview
Problem
Current spin-orbit torque (SOT) type magnetoresistance effect elements have a reversal current density that is not sufficient for high integration and low energy consumption, and the use of heavy metal materials with high electric resistivity leads to high power consumption.
Innovation Solution
A spin current magnetization rotational element with a ferromagnetic metal layer having a lamination structure of [ferromagnetic layer/nonmagnetic layer]n, where the structure is asymmetric to prevent cancellation of pure spin current, and a spin-orbit torque wiring is used to generate a pure spin current for magnetization rotation or reversal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a symmetric lamination structure of [ferromagnetic layer/nonmagnetic layer]n is used, then the structure is simple and easy to manufacture, but the pure spin current is canceled out leading to insufficient magnetization reversal efficiency
Solution Approach 1:
The patent applies asymmetry by making the lamination structure asymmetric, where the ferromagnetic layers have different thicknesses (e.g., first ferromagnetic layer thickness t1 is different from second ferromagnetic layer thickness t2). This asymmetry prevents the cancellation of pure spin current that occurs in symmetric structures, thereby enabling efficient magnetization reversal while maintaining a relatively simple multi-layer fabrication process.
2Power
If heavy metal materials with high electric resistivity are used in spin-orbit torque wiring, then spin orbit torque is enhanced, but power consumption increases
Solution Approach 1:
The patent changes the parameter of layer thickness to optimize performance. By carefully controlling the thickness of ferromagnetic layers and nonmagnetic layers, the structure achieves enhanced spin orbit torque effect while reducing the need for high-resistivity heavy metal materials, thereby lowering power consumption. The asymmetric thickness configuration allows for optimized spin current generation without excessive energy loss.
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 reduces the current density of magnetization rotation or reversal, achieving efficient magnetization reversal with lower power consumption by utilizing an asymmetric lamination structure and pure spin current in SOT-type magnetoresistance effect elements.
Implementation Method 1
as means for reducing a reversal current with a mechanism different from the STT, magnetization reversal using a pure spin current generated by a spin hall effect has attracted attention
Implementation Method 2
The pure spin current, which is generated by the spin hall effect, causes spin-orbit torque (SOT), and causes magnetization reversal by the SOT
Data Source
AI summary
A spin current magnetization rotational element including a first ferromagnetic metal layer in which a magnetization direction is variable, and a spin-orbit torque wiring that extends in a second direction intersecting a first direction that is a plane-orthogonal direction of the first ferromagnetic metal layer, and is joined to the first ferromagnetic metal layer. The first ferromagnetic metal layer has a lamination structure including a plurality of ferromagnetic constituent layers and a plurality of nonmagnetic constituent layers which are respectively interposed between the ferromagnetic constituent layers adjacent to each other. At least one ferromagnetic constituent layer among the plurality of ferromagnetic constituent layers has a film thickness different from a film thickness of the other ferromagnetic constituent layers, and/or at least one nonmagnetic constituent layer among the plurality of nonmagnetic constituent layers has a film thickness different from a film thickness of the other nonmagnetic constituent layers.