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Proceedings Paper

Spin-polarized currents in superconducting films
Author(s): Milos Bozovic; Zoran Radovic
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Paper Abstract

We present a microscopic theory of coherent quantum transport through a superconducting film between two ferromagnetic electrodes. The scattering problem is solved for the general case of ferromagnet/superconductor/ferromagnet (FSF) double-barrier junction, including the interface transparency from metallic to tunnel limit, and the Fermi velocity mismatch. Charge and spin conductance spectra of FSF junctions are calculated for parallel (P) and antiparallel (AP) alignment of the electrode magnetization. Limiting cases of nonmagnetic normal-metal electrodes (NSN) and of incoherent transport are also presented. We focus on two characteristic features of finite size and coherency: subgap tunneling of electrons, and oscillations of the differential conductance. Periodic vanishing of the Andreev reflection at the energies of geometrical resonances above the superconducting gap is a striking consequence of the quasiparticle interference. Also, the non-trivial spin-polarization of the current is found for FSF junctions in AP alignment. This is in contrast with the incoherent transport, where the unpolarized current is accompanied by excess spin accumulation and destruction of superconductivity. Application to spectroscopic measurements of the superconducting gap and the Fermi velocity is also discussed.

Paper Details

Date Published: 7 November 2002
PDF: 12 pages
Proc. SPIE 4811, Superconducting and Related Oxides: Physics and Nanoengineering V, (7 November 2002); doi: 10.1117/12.452478
Show Author Affiliations
Milos Bozovic, Univ. of Belgrade (Serbia)
Zoran Radovic, Univ. of Belgrade (Serbia)


Published in SPIE Proceedings Vol. 4811:
Superconducting and Related Oxides: Physics and Nanoengineering V
Ivan Bozovic; Davor Pavuna, Editor(s)

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