Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 44: Scanning Probe Methods I
O 44.11: Vortrag
Mittwoch, 13. März 2013, 13:00–13:15, H33
Fundamental relation between chemical force and tunneling current driven by quantum degeneracy — Yoshiaki Sugimoto1, Martin Ondráček3, Masayuki Abe1, Seizo Morita1, Pablo Pou2, Rubén Pérez2, Fernando Flores2, and •Pavel Jelínek3 — 1Graduate School of Engineering, Osaka University 2-1, Yamada-Oka, Suita, Osaka 565-0871, Japan — 2Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, E-28049, Spain — 3Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10/112, Prague, 162 00, Czech Republic
Both the tunneling current I and the short-range component of the force F, induced by the formation of the chemical bond, exhibit in atomic contacts an exponential decay with similar characteristic decay length. Consequently, the relation between F and I follows the relation Fn I, where n is an integer number. Over the last 10 years, several different factors n have been proposed by different groups based on both theoretical analysis and experimental measurements; still there is no consensus on the relation between F and I.
We explain origin of two characteristic scaling regimes, where the current is either proportional to the force I∼F or to the square of the chemical force, i.e. I∼F2, as consequence of the quantum degeneracy. We will collate our theoretical prediction with experimental AFM/STM measurements of single atom point contacts and complex DFT simulations to unambiguously prove the existence of these two characteristic regimes.