Dresden 2011 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 61: TR: Nanoelectronics I - Quantum Dots, Wires, Point Contacts 3

TT 61.6: Talk

Friday, March 18, 2011, 12:00–12:15, HSZ 304

Modeling a scanning tunneling microscope: a nano-DΓA study — •Viktoria Motsch, Angelo Valli, Giorgio Sangiovanni, Alessandro Toschi, and Karsten Held — Institut für Festkörperphysik, TU Wien, Österreich

We apply nano-DΓA [1], a new approach to nanoscopic systems based on Dynamical Vertex Approximation (DΓA)[2], to study the tip of a scanning tunneling microscope (STM). Due to the geometrical confinement, we expect electronic correlations to play a more pronounced role in such a system. Decreasing the hybridization strength between the tip and the surface, the atom forming the contact undergoes a local Mott-Hubbard crossover (i.e. we observe a suppression of the spectral weight at the Fermi level). We study this phenomena and compute the conductance through the tip for different lattice structures and set of parameters.Our finding has important implications for interpreting STM images: The presumed proportionality of the conductance to the local density of states of the material scanned does not necessarily hold for STM tips made out of transition metals.
A. Valli, et al., Phys. Rev. Lett. 104, 246402 (2010)
A. Toschi, et al., Phys. Rev. B 75, 045118 (2007)