Dresden 2006 – scientific programme

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TT: Tiefe Temperaturen

TT 26: Transport - Poster Session

TT 26.38: Poster

Wednesday, March 29, 2006, 14:30–18:30, P1

Effects of chemical substitution on quantum transport through single aromatic molecules — •Florian Pump¹, Alessandro Pecchia², Aldo Di Carlo², and Gianaurelio Cuniberti¹ — ¹Institute for Theoretical Physics, University of Regensburg, D-93040 Regensburg, Germany — ²INFM and Department of Electronic Engineering, University of Rome "Tor Vergata" I-00133 Rome, Italy

Recent experimental investigations show that the measurement of unimolecular transport is possible. Still, signatures of truly molecule-mediated quantum transport have to be selectively identified in experiments and their theoretical mechanisms need to be understood. Such signatures can be obtained by separating an aromatic molecule into two electronically different parts. This can be attained by the substitution of certain H-atoms asymmetrically on one side of phenylene ethynylene based molecules by atoms with larger electronegativity (e.g. F). Then, the π-conjugation can be broken by means of steric repulsion groups like NO₂ and/or CH₃. Depending on the position of these groups on the molecule, it is possible to further engineer electrical dipoles able to incrementally break the π-conjugation in response to an external electric field. We have thus investigated nonlinear quantum transport through phenylene ethynylene based molecules as a function of a gatable intra-molecular coupling to understand the role of chemical substitution on the observable nonequilibrium electrical current. Contacts to the recent experiments by Elbing et al. [1] are also provided.

[1] M. Elbing et al., Proc. Natl. Acad. Sci. USA 102, 8815 (2005).