Regensburg 1998 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 10: Postersitzung I: Ladungseffekte in Einelektronensystemen (1-6), Niedrigdimensionale Systeme (7-17), Transporteigenschaften und Pinning in HTSL (18-30), Symmetrie des Ordnungsparameters in HTSL (31-36), Korrelierte Elektronen: Theorie (37-79)
TT 10.13: Poster
Dienstag, 24. März 1998, 09:30–13:00, A
Phase-sensitive transport in normal-/superconductor heterostructures: Crossover from coherent to tunneling conductance — •F.K. Wilhelm1, A.D. Zaikin1, V.N. Antonov2, and H. Takayanagi2 — 1Institut für Theoretische Festkörperphysik, Universität Karlsruhe, 76128 Karlsruhe — 2NTT Basic Research Laboratories, 3-1 Morinosato-Wakamiya, Atsugi-shi, Kanagawa, 243-01 Japan
We report results of theoretical and experimental work on dissipative charge transport in hybrid superconducting/normal structures. Depending on the realization, the conductance of such structures consists of coherent and tunneling contributions. Due to the proximity effect, the former is increased in comparison to the normal state value while the latter is decreased as a gap develops. If a magnetic flux is passed through a loop in a multiply connected S/N-structure, the induced correlations may interfere producing a net supercurrent, and the conductance is modulated. We show in a quasiclassical calculation extending previous work [1], that the oscillations G(Φ) change their sign depending on whether the system contains a tunneling barrier (zero flux minimum) or not (zero flux maximum). We report recent experiments on a normal loop with two superconducting stripes. The loop is contacted by two normal probes, one of which is in good metallic contact and one of which contains artificial tunneling barriers. The results of conductance measurements in this system agree with our theoretical predictions.
[1] A.A.Golubov, F.K.Wilhelm, and A.D.Zaikin, PRB 55, 1123 (1997).