Measuring graphene’s Berry phase at $B=0$ T

Abstract

The Berry phase of wave functions is a key quantity to understand various low-energy properties of matter, among which electric polarisation, orbital magnetism, as well as topological and ultra-relativistic phenomena. Standard approaches to probe the Berry phase in solids rely on the electron dynamics in response to electromagnetic forces. In graphene, probing the Berry phase $\pi $ of the massless relativistic electrons requires an external magnetic field. Here, we show that the Berry phase also affects the static response of the electrons to a single atomic scatterer, through wavefront dislocations in the surrounding standing-wave interference. This provides a new experimental method to measure the graphene Berry phase in the absence of any magnetic field and demonstrates that local disorder can be exploited as probe of topological quantum matter in scanning tunnelling microscopy experiments.

Keywords

• Berry phase
• Graphene
• STM
• Wavefront dislocations
• Topology
• Atomic defect