English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Electronic band structures dictate the mechanical, optical and electricalproperties of crystalline solids. Their experimental determination is thereforeof crucial importance for technological applications. While the spectraldistribution in energy bands is routinely measured by various techniques, it ismore difficult to access the topological properties of band structures such asthe Berry phase {\gamma}. It is usually thought that measuring the Berry phaserequires applying external electromagnetic forces because these allow realizingthe adiabatic transport on closed trajectories along which quantum mechanicalwave-functions pick up the Berry phase. In graphene, the anomalous quantum Halleffect results from the Berry phase {\gamma} = {\pi} picked up by masslessrelativistic electrons along cyclotron orbits and proves the existence of Diraccones. Contradicting this belief, we demonstrate that the Berry phase ofgraphene can be measured in absence of any external magnetic field. We observeedge dislocations in the Friedel oscillations formed at hydrogen atomschemisorbed on graphene. Following Nye and Berry in describing thesetopological defects as phase singularities of complex fields, we show that thenumber of additional wave-fronts in the dislocation is a real space measurementof the pseudo spin winding, i.e. graphene's Berry phase. Since the electronicdispersion can also be retrieved from Friedel oscillations, our studyestablishes the electronic density as a powerful observable to determine boththe dispersion relation and topological properties of wavefunctions. This couldhave profound consequences for the study of the band-structure topology ofrelativistic and gapped phases in solids.

Measuring the Berry phase of graphene from wavefront dislocations in Friedel oscillations