Amorphous Heavy Metal Multilayers for Low-Power SOT-MRAM
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Solution Overview
Problem
The use of β-W as the heavy metal layer in SOT-MRAM elements results in high power consumption due to high electrical resistivity and high variability in MTJ characteristics due to roughness.
Innovation Solution
A magnetic multilayer film with an amorphous heavy metal layer structure, where first layers containing Hf and second layers containing a heavy metal excluding Hf are alternately layered, is used to reduce power consumption and smoothness of the heavy metal layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If β-W is used as the heavy metal layer, then spin-orbit interaction is achieved for magnetization reversal, but power consumption increases due to high electrical resistivity
Solution Approach 1:
The patent employs a composite heavy metal layer structure consisting of alternating Hf-containing layers and heavy metal excluding Hf layers. This composite structure combines the beneficial properties of different materials: Hf provides spin-orbit interaction for efficient magnetization reversal, while the alternating structure reduces electrical resistivity compared to pure β-W, thereby lowering power consumption and reducing MTJ characteristic variability.
Solution Approach 2:
The heavy metal layer is segmented into multiple alternating layers of Hf-containing material and heavy metal excluding Hf. This segmentation allows the system to achieve both low power consumption (through reduced electrical resistivity) and reliable MTJ characteristics (through uniform spin-orbit interaction distributed across multiple interfaces).
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 proposed solution effectively suppresses power consumption and reduces the roughness of the heavy metal layer, thereby mitigating variations in MTJ characteristics.
Implementation Method 1
a spin current is induced when a current is passed through the heavy metal layer as a result of spin-orbit interaction, and the recording layer undergoes magnetization reversal as a result of spins polarized by the spin current flowing into the recording layer
Data Source
AI summary
A magnetic multilayer film for a magnetic memory element includes an amorphous heavy metal layer having a multilayer structure in which a plurality of first layers containing Hf alternate repeatedly with a plurality of second layers containing a heavy metal excluding Hf; and a recording layer that includes a ferromagnetic layer and that is adjacent to the heavy metal layer, the ferromagnetic layer having a variable magnetization direction.