Berlin 2008 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 22: Transport: Poster Session

TT 22.45: Poster

Wednesday, February 27, 2008, 14:00–18:00, Poster B

Influence of chopped laser light onto the electronic transport through atomic-sized contacts — •Kerstin M. C. Hans, Daniel C. Guhr, Dennis Rettinger, Johannes Boneberg, Artur Erbe, Paul Leiderer, and Elke Scheer — Universität Konstanz, Konstanz, Germany

In our experiment we investigate the influence of laser irradiation onto the electrical conductance G of Au nanocontacts established with the mechanically controllable breakjunction (MCB) technique [1]. We concentrate on the study of reversible G changes which can be as high as 50%. We compare results of samples fabricated on different substrate materials. On metal substrates, with high reflectivity in the visible light range and insulated from the MCB, we observe an enhancement of G under almost all conditions [2]. In contrast to this, on pure insulating and full light-absorbing substrates we additionally observe a decrease of G, depending on the position of the laser spot on the sample. Within one series of measurements we have also varied intensity, the polarisation and the wavelength. We discuss several physical mechanisms which might contribute to the observed effect including thermal expansion and photon-assisted transport (PAT) [3]. From the analysis of our data we conclude that PAT is the dominating effect in our experiment on metal substrates and thermal expansion on the insulating substrates. First results with Pt structures on insulated metal substrates will also be shown.

[1] J. M. van Ruitenbeek et al., Rev.Sci. Instrum. 67, 108 (1996)

[2] D. C. Guhr et al., PRL 99, 086801 (2007)

[3] J. K. Viljas and J. C. Cuevas, PRB 75, 075406 (2007)