André Dankert, Saroj P. Dash. Electrical gate control of spin current in van der Waals heterostructures at room temperature. Nature Communications, 2017; 8: 16093 DOI: 10.1038/NCOMMS16093
Graphene Flagship researchers at Chalmers University of Technology in Gothenburg, Sweden have showed a graphene-based spin field-effect transistor operating at room temperature. Using the spin of the electrons in graphene and other layered material heterostructures they have produced working devices as a step towards integrating spintronic logic and memory devices. Current semiconductor logic devices within our computers use the flow and control of electronic charge for information processing. Spintronic memory devices use electron spin to store information. For future devices, researchers are searching for ways to integrate both information processing and storage in one device unit.
“Graphene is an excellent medium for spin transport at room temperature, due to its low atomic mass. However, an unsolved challenge was to control the spin current at ambient temperature” explains Saroj Dash, Associate Professor at Chalmers University of Technology. The Graphene Flagship researchers Andre Dankert and Saroj Dash have now shown that it is possible to electrically manipulate the spin properties of graphene in a controlled manner at room temperature. This not only could open many new possibilities in spin logic operations but also integration with magnetic memory elements in a single device. With further developments, if one could produce a spin current without charge flow, this will require far less power and lead to more versatile devices. This is especially important as we move more and more toward hand held mobile computing.
“Controlling the flow of spin currents in a transistor-like manner is a decade old dream and the missing link towards all-electrical spin logic applications.” says the lead author Andre Dankert from Chalmers University of Technology, Graphene has been shown to transport spin over long distances. Combining graphene with another layered material where spin lasts much less time can produce a spin field-effect transistor like device.
Talking about creating spintronic devices using a heterostructure is Saroj Dash, “By combining graphene, where spin lasts for nano seconds with molybdenum disulfide where spin only lasts for picoseconds you can control where the spin can go by using a gate voltage – essentially you can create a spin switch. Importantly, we show in this research a particular materials mix which enables this spin-switch to work at room temperature.” Andre Dankert said, “Now we know the crucial parameters of our device structure, we can optimise it to increase the effective gain and transistor action.”
Many layered materials are promising for spintronics. In addition to exploring the interesting properties of these individual crystals, it is intriguing to reveal the potential of their heterostructures. The bigger goal is to create novel spin phenomena in layered materials based devices by stacking different layers with complementary properties, Saroj Dash explained. Bart van Wees, leader of the spintronics work package adds, “The future challenge will be to explore and use the new spintronic functionalities which are made possible by the new van der Waals heterostructures. The authors already made an important step here.”
https://graphene-flagship.eu/field-effect-transistor-using-graphenes-electron-spin
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