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TT: Tiefe Temperaturen

TT 26: Transport - Poster Session

TT 26.36: Poster

Mittwoch, 29. März 2006, 14:30–18:30, P1

Hofstadter butterfly of carbon nanotubes — •Norbert Nemec and Gianaurelio Cuniberti — Institut für theoretische Physik, Universität Regensburg, 93040 Regensburg

The electronic spectrum of a two dimensional square lattice in a perpendicular magnetic field, known as Hofstadter butterfly, was discovered in Regensburg thirty years ago [1]. We have calculated the Hofstadter butterfly for carbon nanotubes (CNTs) in the tight-binding approximation. For the case of single wall CNTs, it is straightforward to implement magnetic fields parallel to the tube axis by means of zone-folding in the graphene reciprocal lattice. We have also studied perpendicular magnetic fields which, in contrast to the parallel case, lead to a much richer, non-periodic spectrum. Moreover, we have investigated magnetic fields piercing double-wall CNTs and found strong signatures of inter-shell interaction in the resulting butterfly-spectrum. Ubiquitous to all perpendicular magnetic field spectra is the presence cusp-catastrophes at specific values of energy and magnetic field. At these particular points, the electronic wave function can be correspondingly visualized.

[1] D. Hofstadter, Phys. Rev. B 14, 2239 (1976)