Regensburg 2007 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 8: Superconductivity - Poster Session
TT 8.26: Poster
Monday, March 26, 2007, 14:00–17:45, Poster A
Nonlocal transport in superconductor/normal metal heterostructures — •Jakob Brauer1, Detlef Beckmann1, and Hilbert v. Löhneysen2,3 — 1Forschungszentrum Karlsruhe, INT — 2Forschungszentrum Karlsruhe, IFP — 3Physikalisches Institut, Universität Karlsruhe
Injection of electrons from a normal metal into a superconductor with electron energies below the superconducting gap Δ (measured from the Fermi energy) is only possible by means of Andreev reflection, where an incident electron gets reflected as a hole with opposite spin at the NS interface.
If multiple interfaces are present nonlocal (or crossed) Andreev reflection (CAR) and electron cotunneling (EC) can occur. For an electron injected at an interface A, CAR leads to an emitted hole at a different interface B. On the other hand electron cotunneling yields an emitted electron at B.
To observe these effects we examine samples created by e-beam lithography and shadow evaporation technique. These consist of multiple NS (copper/aluminium) tunnel junctions with spatial seperation of injector and detector contacts of around 150 nm. We present experimental data on local and nonlocal electronic transport measurements.