Dresden 2009 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 8: Postersession Transport: Graphene and Carbon Nanotubes

TT 8.2: Poster

Montag, 23. März 2009, 13:00–16:45, P1B

Time dependent charge and spin transport in graphene nanoribbons — •Claudia Gomes da Rocha, Lakshmi Sankaran, Jens Kunstmann, Luis E.F. Foa Torres, and Gianaurelio Cuniberti — Institute for Materials Science and Max Bergmann Center of Biomaterials, Dresden University of Technology, D-01062 Dresden, Germany

Interesting quantum phenomena can be revealed when low dimensional materials are subject to external fields. In our work we theoretically investigate how external fields influence the transport properties of graphene nanoribbons. We demonstrate that armchair-edge nanoribbons subject to a time-periodic gate potential show the so called quantum wagon-wheel effect, in which Fabry-Perot oscillations can be periodically suppressed or recovered as a function of the AC parameters[1]. For zigzag-edge nanoribbons, more intriguing phenomena take place due to the existence of edge states. Essentially, Fabry-Perot oscillations manifest in a limited range of bias and gate voltages and they cannot be totally recovered by tuning the AC gate. Furthermore, zigzag nanoribbons having a Klein edge are expected to yield spin-polarized bands when described by mean-field Hubbard Hamiltonian. Here we also show that the presence of a DC external gate in zigzag-edge systems suppresses the characteristic edge states. This leads to a transition from a completely spin-polarized semiconducting system to one which is non-magnetic and metallic.

[1] L. E. F. Foa Torres, and G. Cuniberti, cond-mat arXiv. 0807.4953