Berlin 2015 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 89: Graphene: Electronic structure (O with HL/TT)

HL 89.4: Vortrag

Donnerstag, 19. März 2015, 15:45–16:00, MA 041

Size quantization effects in quasiparticle interference on epitaxial graphene nanoflakes — •Julia Tesch¹, Philipp Leicht¹, Felix Blumenschein¹, Anders Bergvall², Tomas Löfwander², Luca Gragnaniello¹, and Mikhail Fonin¹ — ¹Universität Konstanz, Konstanz, Germany — ²Chalmers University of Technology, Göteborg, Sweden

Graphene nanostructures represent an exciting topic for research, as a strong spatial confinement together with the edge structure impose new electronic properties, making them promising candidates for future nanoscale electronic units. Here, we investigate by means of low-temperature scanning tunnelling microscopy and spectroscopy oblong quasi-freestanding epitaxial graphene nanoflakes prepared on Ag(111) and Au(111) by intercalation with virtually no edge bonding [1]. We implement quasiparticle interference (QPI) mapping to analyze standing wave patterns arising from elastic scattering processes within a single nanoflake. The Fourier analysis of the obtained QPI maps shows that in addition to ringlike structures due to the intervalley and intravalley scattering observed for large graphene sheets, additional scattering features are visible, which can be related to the transverse modes in a nanoflake [2]. Our experimental results are supported by tight-binding calculations of realistic flakes, which very well reproduce the experimentally observed fingerprints of confinement in the Fourier transform of the standing wave patterns.

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