NEW YORK — According to new research published at the Massachusetts Institute of Technology (MIT) last week, graphene can host quantum electronic states at its edge due to a spin selectivity of which researchers were previously unaware.
The two-dimensional carbon material can be used in this new way allowing for the discovering of unexpected properties and use cases. Published in the journal Nature, the study shows that graphene also offers, under certain extreme conditions, additional benefits including exotic uses such as quantum computing.
This could ultimately lead to the creation of quantum computers, according to one researcher, although the extreme conditions required would make it necessarily a highly specialized machine for high-priority computational tasks such as national laboratories.
In the study, graphene was placed under an extremely powerful magnetic field at very low temperatures and the direction of the spin of electrons determined the graphene’s ability to filter those electrons -- a task that conventional electronics systems cannot perform.
Researchers found that if a powerful magnetic field is applied to the graphene, its behavior changes as electrons move around the conducting edge either clockwise or counter-clockwise. Under normal circumstances, current flows only along the edges of the graphene while the main part stays insulated. That current moves in one direction according to the quantum Hall effect.
Graphene is used for a variety of different purposes as it stands. However, by varying the magnetic field, researchers found that they could turn edge states on and off, meaning that in principle, it is possible to make circuits and transistors out of the material. This has not been accomplished before in conventional insulators. What’s more, this spin selectivity prevents the disruption of the motion of electrons such that even if the edges are dirty electrons are transmitted along the edges with almost no imperfections.
The paper was published by professors Pablo Jarillo-Herrero and Ray Ashoori, postdocs Andrea Young and Ben Hunt, graduate student Javier Sanchez-Yamaguchi, and several others. The work was supported by grants from the U.S. Department of Energy, the Gordon and Betty Moore Foundation, and the National Science Foundation, and used facilities at the National High Magnetic Field Laboratory in Florida.
According to researchers at MIT, the behavior of the graphene flakes had been predicted, but had never been seen before. Spin-selective behavior has thus, for the first time to date, been demonstrated in a single sheet of graphene, which also marks the first time a transition between the two states has ever been noted.
The research marks a new direction in topological insulators according to researchers, who are not aware of what that may lead to, but note that these developments open up possibilities for the construction of new electrical devices. What’s more, they believe that this work may connect topological insulator physics to the physics of graphene with interactions.
— Zewde Yeraswork, Associate Editor, EE Times