Regensburg 2004 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 17: Postersitzung II: Transport, Quantenkoh
ärenz, Quantenflüssigkeiten

TT 17.32: Poster

Dienstag, 9. März 2004, 14:30–19:00, Poster A

Channel analysis of electrical conductance through a Zn single-atom contact — •Michael Häfner, Jan Heurich, Juan-Carlos Cuevas und Gerd Schön — Institut für Theoretische Festkörperphysik, Universität Karlsruhe, 76128 Karlsruhe

Today it is possible to manipulate atomic-sized structures in a controlled way. Special attention is payed to the electronic transport properties of single-atom contacts. For noble and s-p like metals the conduction is carried by the s-band (one channel) and the s- and p-bands (up to four channels) respectively. Scheer et al. have recently measured the conductance of Zn single-atom contacts. As Zn is intermediate between noble and s-p like metals it constitutes an excellent testbed for the detailed study of the interplay between electronic configuration and conduction properties in this regime.

In this work we present a theoretical analysis of the experiment using tight binding transport calculations. This approach allows us to show how the conduction channels arise from the atomic orbitals and elucidate which specific properties of the individual orbitals determine their contribution to the current. For the case of Zn single-atom contacts we find a typical total transmission of ∼ 0.6 in good agreement with the experiment. In contrast to the noble or s-p like metals, the current is predominantly carried by two channels which can be related to a combination of the s and p valence bands of Zn.