Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 28: Superconductivity: Heterostructures, Andreev Scattering, Proximity Effect, Coexistence
TT 28.3: Vortrag
Mittwoch, 25. März 2009, 16:00–16:15, HSZ 105
Non-local transport in normal-metal/superconductor hybrid structures: the role of interference and interaction — •Jakob Brauer1, Detlef Beckmann1, Florian Hübler1, and Hilbert v. Löhneysen2 — 1Forschungszentrum Karlsruhe, Institut für Nanotechnologie, P.O.-Box 3640, D-76021 Karlsruhe — 2Forschungszentrum Karlsruhe, Institut für Festkörperphysik, P.O.-Box 3640, D-76021 Karlsruhe and Physikalisches Institut, Universität Karlsruhe, D-76128 Karlsruhe, Germany
We present experimental results on non-local conductance in multiterminal hybrid structures, where two normal metal contacts are attached to a single superconductor. For contacts with an insulating tunnel barrier, and at energies below the energy gap of the superconductor, the non-local conductance is determined by the competition of crossed Andreev reflection (CAR) and elastic cotunneling (EC). The contributions of CAR and EC are expected to cancel each other in the tunneling limit. Recently [Russo et al., Phys. Rev. Lett. 95, 027002 (2005)], a non-vanishing signal has been observed in such structures, with an additional energy scale below the gap. So far, quantum interference and Coulomb interaction have been suggested to lift the cancellation of CAR and EC, but no established theory exists for this signal. We observe similar signals in our structures, and demonstrate that the origin is quantum interference.