Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 88: Transport: Carbon Nanotubes
TT 88.1: Talk
Thursday, March 19, 2015, 09:30–09:45, A 053
The excitation spectrum of a carbon nanotube — from 0 to 2 electrons — Daniel Schmid1, Magdalena Marganska2, Siddharth Buddhiraju2, Peter Stiller1, Alois Dirnaichner1, Milena Grifoni2, •Andreas K. Hüttel1, and Christoph Strunk1 — 1Institute for Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany — 2Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany
Defect- and contamination free, suspended single wall carbon nanotubes (CNTs) display a highly regular transport spectrum. The spectral features directly reflect the properties of the underlying graphene lattice, modified by curvature and finite length effects as well as the cylindrical topology of the nanotube.
We present and analyze data on the first two Coulomb blockade oscillations (0 ≤ Nel ≤ 2) of such a system. Sharp differential conductance features enable the observation of multiple excited states of the trapped electronic system in variable angle magnetic fields. The analysis of the Nel=1 data provides us with direct knowledge of the single particle level spectrum. In contrast, the Nel=2 spectrum is dominated by the electron-electron interactions. In both regimes, the spectra are governed by the underlying symmetries of the CNT Hamiltonian.
Our model is based on a minimal one-shell Hamiltonian of a CNT with spin-orbit coupling and valley mixing and taking into account a magnetic field, extended to include two shells and the exchange interaction.