Regensburg 2004 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 19: Supraleitung: Heterostrukturen, Andreev-Streuung, Proximity-Effekt, Koexistenz

TT 19.5: Vortrag

Mittwoch, 10. März 2004, 18:00–18:15, H20

Experimental detection of the current phase relation in SNS Josephson contacts — •Johannes Bentner, Andreas Bauer, Matthias Reinwald, Werner Wegscheider, and Christoph Strunk — Institut für experimentelle und angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053 Regensburg

Short superconductor/normalconductor weak links (SNS) are expected to show a non-sinusodial current phase relation. This is due to a relativ high transmission probability, and hence the Cooper pairs are not transfered uncorrelated, but in Clusters of n correlated pairs. We present direct measurements of the current phase relation of Al/Au/Al and Al/Ag/Al SNS weak links prepared by shadow evaporation. Micropatterned GaAs-AlGaAs Hall-sensors are used to measure the flux which is generated by the circulating supercurrent in Al loops containing a single SNS junction. The supercurrent is generated by the phase difference across the junction which is controlled by applying an external magnetic flux to the loop. In highly transparent Al/Ag junctions we find a non-sinusoidal current phase relation. In contrast to that, in Al/Au junctions with lower transparency the standard sinusoidal behavior is found. The critical current extracted from the measured current phase relations agrees well with transport measurements of simliar control samples.