Quantum degeneracy in atomic point contacts revealed by chemical force and conductance

0399566 - FZÚ 2014 RIV US eng J - Journal Article
Sugimoto, Y. - Ondráček, Martin - Abe, M. - Pou, P. - Morita, S. - Perez, R. - Flores, F. - Jelínek, Pavel
Quantum degeneracy in atomic point contacts revealed by chemical force and conductance.
Physical Review Letters. Roč. 111, č. 10 (2013), "106803-1"-"106803-5". ISSN 0031-9007. E-ISSN 1079-7114
R&D Projects: GA ČR(CZ) GPP204/11/P578
Grant - others:GA AV ČR(CZ) M100101207
Institutional support: RVO:68378271
Keywords : scanning tunneling microscopy * atomic force microscopy * degenerate states * silicon surface * dangling bonds
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 7.728, year: 2013

Quantum degeneracy is an important concept in quantum mechanics with large implications to many processes in condensed matter. We show the consequences of electron energy level degeneracy on the conductance and the chemical force between two bodies at the atomic scale. We propose a novel way in which a scanning probe microscope can detect the presence of degenerate states in atomic-sized contacts even at room temperature. The tunneling conductance G and chemical binding force F between two bodies both tend to decay exponentially with distance in a certain distance range, usually maintaining direct proportionality to each other. However, we show that a square relation, G proportional to F squared, arises as a consequence of quantum degeneracy between the interacting frontier states of the scanning tip and a surface atom. We demonstrate this phenomenon on the Si(111)-(7×7) surface reconstruction.
Permanent Link: http://hdl.handle.net/11104/0226828