Spin-Current Magnetic Memory With 2D Free Layer for Fast Low-Current Switching
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Solution Overview
Problem
Current magnetic memory devices using spin current face challenges in achieving high-speed switching characteristics, high durability, and low operating current density, while also striving to increase integration density.
Innovation Solution
A magnetic memory device utilizing a spin current with a data storage layer comprising a pinned layer and a free layer, where the free layer is made of a two-dimensional van der Waals material with spin Hall effect and metal properties, and the wirings contacting these layers are designed to generate spin currents with specific operating currents to switch the magnetic moment without external magnetic fields, thereby reducing coercive force and enhancing integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional magnetic memory device uses a spin current for switching, then the magnetic moment direction can be changed, but the switching speed is limited and operating current density is high
Solution Approach 1:
The patent changes the material parameter of the free layer from conventional ferromagnetic material to two-dimensional van der Waals material with strong spin-orbit coupling. This material parameter change enables much faster magnetization switching (sub-picosecond scale) and significantly reduces the operating current density required for switching operations.
Solution Approach 2:
The patent employs a composite structure combining two-dimensional van der Waals material with a magnetic tunnel junction (MTJ) structure. The van der Waals material layer is integrated with the MTJ stack (pinned layer, tunnel barrier, free layer), creating a composite system that leverages both the fast switching characteristics of the van der Waals material and the high TMR ratio of the MTJ structure.
2Reliability
If the magnetic memory device uses a pinned layer and free layer structure, then data storage is enabled, but the device complexity increases
Solution Approach 1:
The patent extracts the magnetic moment switching function from the conventional spin transfer torque mechanism and relocates it to the two-dimensional van der Waals material layer. This extraction allows the pinned layer structure to be simplified while maintaining data storage capability, as the van der Waals material handles the dynamic switching while the pinned layer provides the reference magnetization.
Solution Approach 2:
The two-dimensional van der Waals material layer serves multiple functions simultaneously: it acts as the free layer for magnetization switching, provides the spin-orbit coupling mechanism for fast switching, and enables low-current-density operation. This multi-functionality reduces the need for additional specialized layers, thereby simplifying the overall device structure.
3Speed
If a two-dimensional van der Waals material is used for the free layer, then high-speed switching and low current density are achieved, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses two-dimensional van der Waals material which inherently forms atomically thin and uniform films. These thin-film characteristics enable precise thickness control and uniform material properties across the device area, meeting the stringent manufacturing precision requirements while enabling the desired high-speed switching performance.
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 configuration enables high-speed switching, improved durability, and reduced operating current density, while maintaining high integration density and separating the write and read paths, thus addressing the limitations of existing technologies.
Implementation Method 1
the free layer includes a two-dimensional material having a spin Hall effect, magnetic properties, and metal properties
Implementation Method 2
A magnetic memory device records or reads information using a tunneling magnetoresistance (TMR) phenomenon
Data Source
AI summary
Provided are a magnetic memory using a spin current, an operating method thereof, and/or an electronic apparatus including the magnetic memory. The magnetic memory includes, first and second wirings spaced apart from each other and intersecting each other, and a data storage layer between the first and second wirings. The data storage layer includes a pinned layer with a fixed magnetic moment, a free layer spaced apart from the pinned layer and not having a fixed magnetic moment, and an insulating tunnel barrier layer provided between the pinned layer and the free layer. Among the first and second wirings, the wiring contacting the free layer includes a conductive wiring having no spin Hall effect, and the free layer includes a two-dimensional material which at room temperature has a spin Hall effect, magnetic properties, and metal properties. The two-dimensional material includes a two-dimensional van der Waals material.