Researchers from Kiel University have reported a previously unknown effect in graphene. Dr. Jan-Philip Joost and Professor Michael Bonitz showed, for the first time, that light pulses can generate electrons at specific designated locations in the material. To investigate how electrons move and interact, they simulated the effects of laser pulses on small graphene clusters. Their results could open up new approaches for nanoelectronics.
Ultrashort laser pulses can act like light switches on the nanoscale, switching electrons on and off at precisely defined spots within femtoseconds. When a pulse strikes a graphene cluster, electrons gather at one edge. A second pulse can generate electrons almost instantly at a different site. The researchers can steer the electrons with high precision, like a traffic signal guiding them where to go.
"We discovered this spatial selectivity in a chemically completely homogeneous material - graphene consists solely of carbon," explains Bonitz. "Until now, such an effect was only known in molecules composed of different atoms with distinct absorption properties. In our graphene clusters, control emerges solely from the electronic structure and from special topological states. Even under small perturbations, the electron positions remain stable, making the control reliable."
The findings of the study could mark a step forward for next-generation electronics. Today's transistors operate in the gigahertz range. Graphene-based components switched by laser pulses could function in the petahertz range - up to 10,000 times faster.
In communication systems, precisely guided electron pathways could enable rapid data transfer with minimal energy consumption. This opens up possibilities for high-performance computing, AI chips, and other ultra-fast electronic systems. The challenge now is to integrate the excited electrons reliably into actual circuits.
"If these processes can be transferred into real devices, it would be a huge leap for nanoelectronics," says Joost.
