Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 54: Transport: Carbon Nanotubes

TT 54.4: Vortrag

Mittwoch, 9. März 2016, 15:45–16:00, H22

Secondary interference from trigonal warping in clean carbon-nanotubes — Alois Dirnaichner^1,2, •Miriam del Valle², Karl Götz¹, Felix Schupp¹, Nicola Paradiso¹, Milena Grifoni², Andreas Hüttel¹, and Christoph Strunk¹ — ¹Institute for Experimental and Applied Physics, University of Regensburg — ²Institute for Theoretical Physics, University of Regensburg

We investigate experimentally and theoretically a Fabry-Perot resonator based on a clean carbon nanotube. The trigonal warping of the Dirac cones away from the charge degeneracy point leads to a superstructure in the interference pattern. This secondary interference results from the presence of the valley degree of freedom. Single wall carbon nanotubes can be classified to be either zigzag, armchair, zigzag-like, or armchair-like. In any armchair case two interferometer channels with different wave vectors exist; specifically in the armchair-like (chiral with finite-k_∥ Dirac point) nanotube case these two channels additionally mix on reflection at the interferometer ends. The wave vector difference depends on the chiral angle; this way we can use the resulting slow modulation of the average conductance to estimate the chiral angle of the measured nanotube. 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.