Regensburg 2016 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 9: Graphene I: Structure and Dynamics

HL 9.2: Vortrag

Montag, 7. März 2016, 10:45–11:00, H24

Confinement effects in quasiparticle interference on epitaxial graphene nanoflakes — •Julia Tesch¹, Philipp Leicht¹, Felix Blumenschein¹, Tomas Löfwander², Luca Gragnaniello¹, and Mikhail Fonin¹ — ¹Universität Konstanz, Konstanz, Germany — ²Chalmers University of Technology, Göteborg, Sweden

In the search for suitable materials to be used in nanoscale electronic devices, graphene quantum dots, ribbons and flakes have attracted increased attention amongst researchers, as they allow for a combination of graphene’s linear electronic dispersion relation with interesting physical phenomena arising from the size quantization of the structures.

We present a comprehensive study of epitaxial graphene nanoflakes on noble metal surfaces by means of low-temperature scanning tuneling microscopy and spectroscopy. The analysis of quasiparticle interference patterns produced by elastic scattering at defects allows for a clear identification of graphene-related contributions visible as ringlike inter- and intravalley features within the Fourier transform images [1]. Lateral electronic confinement within these elongated flakes gives rise to additional scattering intensity related to transitions between the flake’s transverse modes [2]. Additionally, we discuss the influence of edge configuration, lattice symmetry breaking and quasiparticle lifetime on the scattering, by comparison of the experimental results with tight-binding calculations of realistic graphene nanoflakes.

[1] P. Leicht et al., ACS Nano 8, 3735 (2014); [2] A. Bergvall et al., Phys. Rev. B 87, 205431 (2013).