Graphene is often described as a pristine material with outstanding charge mobilities. However, even the most pristine material has to be supported by a substrate, and scattering caused by the substrate can have an adverse effect on the electronic properties of graphene. So far the highest charge mobilities in graphene have been seen for epitaxial and suspended samples.

Now, Milan Orlita and co-workers have shown that using bulk graphite — which contains many layers of graphene — as a substrate outperforms both of these arrangements1. Building on previous work on graphite-supported graphene performed at Rutgers University, Orlita and co-workers — who are based at the Grenoble High Magnetic Field Laboratory, Charles University and the Academy of Sciences of the Czech Republic — drove electrons in their graphene sample into circular orbits by exposing them to microwave radiation and an applied magnetic field. The orbital energies showed quantization into so-called Landau levels at unusually weak magnetic fields (1 mT) and high temperatures (50 K).

This quantization implied a carrier mobility of greater than 107 cm2 V−1s−1, which is about one hundred times higher than that in suspended or epitaxial samples. Although the researchers did not measure the electrical characteristics of their sample directly, their results suggest that the limits of mobility in graphene are even higher than previously thought.