Berlin 2005 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 23: Posters Superconductivity, Solids at Low Temperature
TT 23.53: Poster
Montag, 7. März 2005, 14:00–18:00, Poster TU D
Andreev reflection in nanostructured Al/Ni point contacts — •D. Weissenberger1,2, F. Pérez-Willard2,3, C. Sürgers1,2, and H. v. Löhneysen1,2,4 — 1Physikalisches Institut, Universität Karlsruhe, D-76128 Karlsruhe — 2DFG Center for Functional Nanostructures (CFN), Universität Karlsruhe, D-76128 Karlsruhe — 3Laboratorium für Elektronenmikroskopie, Universität Karlsruhe, D-76128 Karlsruhe — 4Forschungszentrum Karlsruhe, Institut für Festkörperphysik, D-76021 Karlsruhe
The electronic transport through nanostructured Al/Ni contacts is studied by point-contact spectroscopy at low temperatures. Samples were fabricated by means of electron-beam lithography, reactive ion etching, and deposition of Al and Ni onto both sides of a Si3N4 membrane as previously reported [1]. Andreev spectra, i.e. conductance vs. voltage, were measured in dependence of temperature and applied magnetic field. The degree of current spin polarization P is obtained by fitting the whole set of experimental data with a theoretical model [1] which takes into account the spin-dependent transmission coefficients due to the majority and minority spin bands of the ferromagnet. For Ni the value of P determined from the spectra is smaller than for Co reported earlier [1].
[1] F. Pérez-Willard et al., Phys. Rev. B 69, 140502(R) (2004)