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TT: Tiefe Temperaturen

TT 9: Transport: Nanoelectronics III - Molecular Electronics

TT 9.14: Vortrag

Montag, 27. März 2006, 17:30–17:45, HSZ 304

Multifractal energy spectra and anomalous diffusion properties of wave packets in incommensurate double-walled carbon nanotubes — •Shidong Wang and Milena Grifoni — Theoretische Physik, Universität Regensburg, 93053 Regensburg

We calculate the energy spectra of incommensurate doubled-walled carbon nanotubes (DWNTs) by approximating the structures with closely related commensurate ones. The energy spectra show multifractal properties. By using the relation between the moments of wave packets and the multifractal dimensions of the energy spectra (F. Piéchon PRL 76, 4372 (1996)), we obtain the diffusive exponent σ₂, where ⟨ x² ⟩ ∼ t^2σ₂. The exponent σ₂ strongly depends on the coupling between shells varying from σ → 1/2 (diffusive limit) for very strong coupling to σ → 1 (ballistic limit) for weak coupling. We compare our results with numerical estimates of σ₂ of wave packets in incommensurate DWNTs (S. Roche et al. PRB 64, 121041 (2001); PLA 285, 94 (2001)), and we obtain very good quantitative agreement.