Scientists from the University of York and Roma Tre University claim that ultra-low-power transistors could be built using composite materials featuring monolayers of graphene and transition metal dichalcogenides (TMDC). These materials, they note, could be used to achieve fine electrical control over electron spin.

York researcher Dr Aires Ferreira said: “For many years, we have been searching for good conductors allowing efficient electrical control over the electron’s spin.

“We found this can be achieved with little effort when 2D graphene is paired with certain semiconducting layered materials. Our calculations show that the application of small voltages across the graphene layer induces a net polarisation of conduction spins.

The team showed that when a small current is passed through the graphene layer, the electrons’ spin polarise in plane due to ‘spin-orbital’ forces brought about by the proximity to the TMDC base. They also showed the efficiency of charge-to-spin conversion can be quite high, even at room temperature.

Professor Roberto Raimondi, who leads the spintronics group at Roma Tre University, noted: “The possibility of orienting the electron spin with electrical currents is attracting a lot of attention in the spintronics community and arises generally as a consequence of specific symmetry conditions.

“As such this phenomenon represents a perfect example where fundamental and applied research go happily together. In this respect, our calculations demonstrate that graphene combined with the transition metal dichalcogenides is an ideal platform where abstract theoretical principles may find immediate application in showing the way to experimental and technological development.”

Dr Ferreira believes the work will attract ‘substantial interest’ from the spintronics community. “The flexible, atomically thin nature of the graphene-based structure is a major advantage for applications. Also, the presence of a semiconducting component opens up the possibility for integration with optical communication networks.”

By: DocMemory
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