Regensburg 2007 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 18: Nanoelectronics I - Quantum Dots, Wires, Point Contacts

TT 18.9: Vortrag

Mittwoch, 28. März 2007, 16:15–16:30, H19

Linear and nonlinear transport across carbon nanotube quantum dots — •Leonhard Mayrhofer and Milena Grifoni — Theoretische Physik, Universität Regensburg, 93040 Regensburg, Germany

We present a low energy-theory for non-linear transport in finite-size interacting single-wall carbon nanotubes. It is based on a microscopic model for the interacting p_z electrons and successive bosonization. We consider weak coupling to the leads and derive equations of motion for the reduced density matrix. We focus on the case of large-diameter nanotubes where exchange effects can be neglected. In this situation the energy spectrum is highly degenerate. Due to the multiple degeneracy, diagonal as well as off-diagonal (coherences) elements of the density matrix contribute to the nonlinear transport. At low bias, a four-electron periodicity with a characteristic ratio between adjacent peaks is predicted. Our results are in quantitative agreement with recent experiments.
L. Mayrhofer, M. Grifoni, Phys. Rev. B 74, 121403(R) (2006).
L. Mayrhofer, M. Grifoni, cond-mat/0612286 (2006).