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TU Dresden » Faculty of Mechanical Science and Engineering » Institute for Materials Science » Chair of Materials Science and Nanotechnology

» presentations   » 2008.11.04-06

Electromechanical Interplay of Carbon Based Nanostructures

M. Poetschke, C. G. Rocha, and G. Cuniberti

Max Bergmann Symposium 2008

2008.11.04-06; Max Bergmann Center, Dresden, Germany

Electromechanical interactions on the nanoscale materials are a field of great interest these days. For this reason, we investigated the changes of transport properties in carbon nanotubes and nanoribbons under the influence of external perturbations with the help of a density functional tight binding model. There we focused mechanical tensions, modeled at the atomic scale employing semiemperical Tersoff potential. It is shown, that applying coaxial forces to a nanotube in the low temperature regime leads to a transition from metallic to semiconducting and vice versa. This is interpreted in the context of graphene's band structure. The recent publication of experimental data [1] to the problem of a doublewall carbon nanotube shell gliding, first discussed in the groundbreaking paper by Saito et al [2] inspired us to look systematically at the special role of incommensurable systems and their particular properties. The model for the mechanic interactions is based on van der Waals potential, but does not necessarily depend on it. A computationally advantageous method of calculations allows the theoretical description of extreme large setups. Therefore, it is found that the incommensurable doublewalls suffer from a rapid decrease of the potential barrier with the system's length and thus the hard direction of sliding is more and more facilitated. In view of conductance it seems possible to detect the shell sliding movement electronically. In a different fashion, we also present investigations about the Fabry-Perot interference patterns in graphene nanoribbons under the effects caused by time dependent excitations. In particular, it was already shown by L.E.F. Foa Torres and G. Cuniberti that Fabry-Perot interference patterns of carbon nanotube systems can be controlled and even suppressed under the influence of AC gating. In this sense, we expect to extract the same strong modifications on conductance curves varying the AC field parameters (intensity and frequency) and the dimensions of the nanoribbon. Additional interesting effects can also be observed due to the existence of edge-states associated with particular geometries of nanoribbons.
[1] DOI: 10.1126/science.1155559
[3] arXiv:0807.4953v2

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