Graphene is a remarkable type of carbon, built from a single layer of tightly connected atoms that is just one atom thick. Despite its thinness, it is extremely stable and conducts electricity extremely well. Due to these qualities, graphene is taken into account a “miracle material” and is already being explored for flexible electronic screens, highly sensitive sensors, advanced batteries, and next-generation solar cells.
A brand new study led by the University of Göttingen, in collaboration with teams in Braunschweig, Bremen, and Fribourg, shows that graphene could also be able to much more. For the primary time, scientists have directly observed “Floquet effects” in graphene. This finding settles a long-running scientific query: Floquet engineering, a method during which light pulses precisely modify the properties of a cloth, may function in metallic and semi-metallic quantum materials akin to graphene. The research appears in Nature Physics.
Direct Evidence of Floquet States in Graphene
To probe these effects, the team used femtosecond momentum microscopy, a technique that permits researchers to capture extremely fast changes in electronic behavior. The graphene samples were illuminated with rapid bursts of sunshine after which examined with a delayed pulse to follow how the electrons responded over ultrashort timescales.
“Our measurements clearly prove that ‘Floquet effects’ occur within the photoemission spectrum of graphene,” says Dr. Marco Merboldt of the University of Göttingen, the study’s first writer. “This makes it clear that Floquet engineering actually works in these systems — and the potential of this discovery is big.” Their results exhibit that Floquet engineering is effective in a wide selection of materials. This brings scientists closer to the flexibility to shape quantum materials with specific characteristics using laser pulses inside extremely short intervals.
Light-Controlled Quantum Materials for Future Technologies
With the ability to tune materials with such precision could lay the groundwork for future electronics, computers, and highly advanced sensors. Professor Marcel Reutzel, who led the project in Göttingen along with Professor Stefan Mathias, explains: “Our results open up latest ways of controlling electronic states in quantum materials with light. This may lead to technologies during which electrons are manipulated in a targeted and controlled manner.”
Reutzel continues: “What is especially exciting is that this also enables us to analyze topological properties. These are special, very stable properties which have great potential for developing reliable quantum computers or latest sensors for the longer term.”
This research was supported by the German Research Foundation (DFG) through Göttingen University’s Collaborative Research Centre “Control of Energy Conversion at Atomic Scales.”