Unlocking the potential of graphene for future electronics

Graphene is an extraordinary material — a sheet of interlocking carbon atoms just one atom thick that is stable and extremely conductive. This makes it useful in a range of areas, such as flexible electronic displays, highly precise sensors, powerful batteries and efficient solar cells. A new study — led by the University of Göttingen, working together with colleagues from Braunschweig and Bremen in Germany, and Fribourg in Switzerland — now takes graphene’s potential to a whole new level.

Researchers have directly observed ‘Floquet effects’ in graphene, thereby resolving a longstanding debate: Floquet engineering — a method in which the properties of a material are very precisely altered using pulses of light — also works in metallic and semi-metallic quantum materials such as graphene. The study has been published in Nature Physics.

The researchers used femtosecond momentum microscopy to experimentally investigate Floquet states in graphene. In this technique, the samples are first excited with rapid flashes of light and then examined with a delayed light pulse in order to track dynamic processes in the material.

“Our measurements clearly prove that ‘Floquet effects’ occur in the photoemission spectrum of graphene,” said Dr Marco Merboldt, physicist at the University of Göttingen and first author of the study. “This makes it clear that Floquet engineering actually works in these systems — and the potential of this discovery is huge.”

The study shows that Floquet engineering works in many materials. This means the goal of designing quantum materials with specific properties — and doing so with laser pulses in an extremely short time — is getting closer.

Tailoring materials in this way for specific applications could form the basis for the electronics, computer and sensor technology of the future. Professor Marcel Reutzel, who led the research in Göttingen together with Professor Stefan Mathias, said, “Our results open up new ways of controlling electronic states in quantum materials with light. This could lead to technologies in which electrons are manipulated in a targeted and controlled manner.

“What is particularly exciting is that this also enables us to investigate topological properties. These are special, very stable properties which have great potential for developing reliable quantum computers or new sensors for the future,” Reutzel said.

Top image caption: The phenomenon in physics known as ‘Floquet states’, which has now been observed in graphene for the first time, as envisaged by artist Lina Segerer. This image, dubbed ‘Dirac Cones I’, explores the concept of Floquet states in graphene generated by light pulses. The painting shows the three-dimensional electronic structure of graphene — known as Dirac cones — and their replicas created by light. Image credit: Lina Segerer.