Dresden 2017 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 75: Poster Session: Transport 1
TT 75.26: Poster
Donnerstag, 23. März 2017, 15:00–19:00, P2-EG
Determining the carbon nanotube chiral angle from electronic Fabry-Perot interference — Alois Dirnaichner1,2, Miriam del Valle2, Karl Götz1, Felix Schupp1, Nicola Paradiso1, Milena Grifoni2, Christoph Strunk1, and •Andreas K. Hüttel1 — 1Institute for Experimental and Applied Physics, Universität Regensburg, Regensburg, Germany — 2Institute for Theoretical Physics, Universität Regensburg, Regensburg, Germany
Connecting low-temperature transport spectroscopy features with a specific microscopic nanotube structure has been an elusive goal so far. While in Coulomb blockade many aspects of the discrete level spectrum are well-understood, a closer look leads to fascinating (and puzzling) hard questions. Here, we apply a complementary approach and analyze the Fabry-Perot interference pattern of a carbon nanotube strongly coupled to metallic leads. By tuning a gate voltage over a large range, the trigonal warping of the Dirac cones can be probed. This, in combination with the valley degree of freedom, leads to a superstructure in the interference pattern, i.e., a secondary interference.
Measurements on an ultraclean, long and suspended carbon nanotube device at millikelvin temperatures are complemented with tight binding calculations of the transmission for specific chiralities and analytic modelling. Taking symmetry classes of nanotubes, but also effects of symmetry breaking at the contacts into account, we show that the crucial parameter for the robust secondary interference pattern is the chiral angle. Consequently, the pattern provides valuable information for determining the structure of a carbon nanotube device.