Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 64: Superconductivity: Heterostructures, Andreev Scattering, Vortex Physics
TT 64.2: Vortrag
Donnerstag, 14. März 2013, 15:15–15:30, H21
Subgap-anomalies in 3-terminal hybrid superconductor/normal metal nanostructures — •Andreas H. Pfeffer1,2, Hervé Courtois3, and François Lefloch1 — 1CEA/INAC/SPSMS, Grenoble, France — 2Nanoscience Foundation (RTRA), Grenoble, France — 3CNRS/Néel Institute and UJF, Grenoble, France
We have studied the electronic transport properties of three terminal superconductor (S) - normal metal (N) - superconductor (S) nano-devices using a new SQUID-based experimental set-up working at very low temperature (30 mK) and dedicated for high sensitive conductance and current noise correlations measurements [1]. In a geometry where a T-shaped normal metal (Cu) is connected to three superconducting reservoirs (Al), new subgap anomalies appear in the differential conductance for specific values of the chemical potential applied to the superconductors. The most emphasized line appears when two superconductors (collectors) are biased at opposite voltage with respect to the third superconducting electrode (injector). This anomaly is consistent with the prediction of non-local quartets as the result of double crossed Andreev reflections (dCAR)[2]. In this particular process, a Cooper pair originating from the injector is split in two quasiparticles that recombine into Cooper pairs in each of the two collectors. Additional features appear for other integer voltage ratios and could be attributed to higher order processes of dCAR. The mechanism of non-local quartet opens perspectives toward a new generation of entanglers.
[1] PRL 107, 077005 (2011); RSI 83, 115107 (2012)
PRL 106, 257005 (2011)