Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 11: Superconductivity: Heterostructures, Andreev Scattering, Proximity Effect, Coexistence
TT 11.7: Vortrag
Dienstag, 28. März 2006, 11:00–11:15, HSZ 301
Spin-dependent Transport Through Nanostructured S/F Point Contacts — •M. Stokmaier1, G. Goll1, C. Sürgers1,2, D. Weissenberger3, F. Pérez-Willard2,3, and H. v. Löhneysen1,2,4 — 1Physikalisches Institut, Universität Karlsruhe — 2DFG Center for Functional Nanostructures (CFN), Universität Karlsruhe — 3Laboratorium für Elektronenmikroskopie, Universität Karlsruhe — 4Forschungszentrum Karlsruhe, Institut für Festkörperphysik
Andreev reflection at the superconductor/ferromagnet (S/F) interface in a ballistic point contact strongly depends on the degree of spin polarization of the ferromagnetic electrode. The spin polarization of the current can be determined by analysis of point-contact spectra using a theoretical model which takes into account two spin-dependent transmission coefficients for the majority and minority charge carriers of the ferromagnet [1]. Here we study the spin-dependent transport through nanostructured Al/Fe point contacts. The samples have been fabricated by deposition of Al and Fe on either side of a thin Si3N4 membrane with a nanostructured hole in it. Differential conductance measurements G(V) have been performed in a dilution refrigerator at temperatures T≥ 20 mK and various magnetic fields. These results are compared with previous data taken on Al/Co and Al/Ni point contacts in order to determine
how the current spin-polarization is related to the spin polarization of the bulk magnetic material.
[1] F. Pérez-Willard et al., Phys. Rev. B 69, 140502(R) (2004).