Electrons Are Snake Charmed Across Graphene
While graphene continues to gain new two-dimensional (2-D) competitors, there’s no getting around its amazing ability to let electrons pass through it with so little resistance that electrons almost behave like photons.
Physicists at the University of Basel in Switzerland have been so focused on this capability that years of experimentation with the one-atom-thick sheets of carbon have led them to discover that it’s possible to direct the electrons in graphene across a predefined path.
In research published in the journal Nature Communications, the scientists discovered that when they stretched, or otherwise manipulated, the honeycomb structure of the graphene and applied both an electrical and magnetic field to it, they could direct the flow of electrons. This marks the first time that anyone has successfully switched the guidance of electrons on and off and guided them without any loss.
The researchers stretched the graphene between two silver electrical contacts and two gold control electrodes that provide the electric field. They then applied a magnetic field perpendicular to the graphene.
The mechanism by which the researchers were able to perform this on-off switching phenomenon can only be achieved in graphene, so other 2-D materials need not apply. It is, in fact, graphene’s lack of a band gap—which has so vexed researchers trying to apply the material to electronics—that is the quality necessary for this type of switching.
By combining the electrical field and magnetic field in this way, the researchers have exploited this capability so that they can induce the electrons to move along a snake pattern: the line bends to the right, then to the left.
“A nano-switch of this type in graphene can be incorporated into a wide variety of devices and operated simply by altering the magnetic field or the electrical field,” said Christian Schönenberger, one of the researchers, in a press release.
As Walt de Heer at the Georgia Institute of Technology suggested last year when it was shown that that electrons behave like photons in graphene nanoribbons (link provided above), this could open a new way to approach the development of electronics.
“This work shows that we can control graphene electrons in very different ways because the properties are really exceptional,” de Heer said at the time about his own research. “This could result in a new class of coherent electronic devices based on room temperature ballistic transport in graphene. Such devices would be very different from what we make today in silicon.”