Size doesn’t matter when it comes to graphene

20 May 2016

Graphene’s latest trick? Electricity is everywhere, all at once. That’s according to a new piece of research that looked at how currents flow through the wonder material.

After measuring flow through narrow constrictions in sheets of graphene, theoretical physicist Florian Libisch and his colleagues now think that “quantum effects” determine the flow of power, rather than space.

That’s not to say incredibly narrow tunnels of graphene can let currents through at the same rate as far wider examples, however, the increase in flow doesn’t grow gradually as the size widens.

“It jumps at certain points,” said Libisch, whose work was published today. “This is a clear indication of quantum effects. The electron is not confined to one particular carbon atom, in some sense, it is located everywhere at the same time.”

Calling the electric current “quantised”, Libisch’s work shows that increased energy into electrons decreases wavelengths, making them fit through constrictions.

Electron wave passing through a narrow constriction, via TU Wien

Electron wave passing through a narrow constriction, via TU Wien

Ups and downs

“At some point, one wavelength fits through the constriction, then two wavelengths, then three – this way the electron flux increases in characteristic steps.”

Graphene has become theoretical physics’ poster child, with researchers keen to learn how this ultra-thin, superconducting material reacts when combined with the likes of boron nitride, which was used in this experiment.

“One thing is for sure: whoever wants to understand tomorrow’s electronics has to know a lot about quantum physics,” said Libisch.

Mexican hat

Earlier this week, scientists developed a new type of graphene-based transistor, which has ‘ultra-low power consumption’, enabling processor clock speeds to increase dramatically.

Dmitry Svintsov, author of a study published in Scientific Reports, claims that the application of a tiny voltage to the gate of the transistor sees “a huge number” of electrons in this tightly-packed hat rim tunnel concurrently.

This causes a sharp change in current from the application of a small voltage, and this low voltage is the reason for the record low power consumption.

Gordon Hunt was a journalist with Silicon Republic