Secondary electron interference from trigonal warping in clean carbon nanotubes

摘要

We investigate Fabry-Perot interference in an ultraclean carbon nanotuberesonator. The conductance shows a clear superstructure superimposed ontoconventional Fabry-Perot oscillations. A sliding average over the fastoscillations reveals a characteristic slow modulation of the conductance as afunction of the gate voltage. We identify the origin of this secondaryinterference in intervalley and intravalley backscattering processes whichinvolve wave vectors of different magnitude, reflecting the trigonal warping ofthe Dirac cones. As a consequence, the analysis of the secondary interferencepattern allows us to estimate the chiral angle of the carbon nanotube.