Julia's paper online (Phys. Rev. B 2017)
Impurity scattering and size quantization effects in a single graphene nanoflake
J. Tesch, P. Leicht, F. Blumenschein, L. Gragnaniello, A. Bergvall, T. Löfwander, and M. Fonin
Phys. Rev. B 95, 155428 (2017).
By using Fourier-transform scanning tunneling spectroscopy we measure the interference patterns produced by the impurity scattering of confined Dirac quasiparticles in epitaxial graphene nanoflakes. Upon comparison of the experimental results with tight-binding calculations of realistic model flakes, we show that the characteristic features observed in the Fourier-transformed local density of states are related to scattering between different transverse modes (subbands) of a graphene nanoflake and allow direct insight into the gapped electronic spectrum of graphene. We also observe a strong reduction of quasiparticle lifetime which is attributed to the interaction with the underlying substrate. In addition, we show that the distribution of the on-site energies at flower defects leads to an effectively broken pseudospin selection rule, where intravalley backscattering is allowed.