Regensburg 2010 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 7: SC: Heterostructures, Andreev Scattering, Proximity Effect, Coexistence

TT 7.5: Talk

Monday, March 22, 2010, 15:00–15:15, H20

Theory of superconductor-ferromagnet point-contact spectra: the case of strong spin-polarization — •Roland Grein¹, Tomas Löfwander², Georgo Metalidis¹, and Matthias Eschrig³ — ¹Institut für Theoretische Festkörperphysik und DFG-Zentrum für funktionelle Nanostrukturen, Karlsruher Institut für Technologie, D-76128 Karlsruhe — ²Department of Microtechnology and Nanoscience MC2, Chalmers University of Technology, S-412 96 Göteborg, Sweden — ³Fachbereich Physik, Universität Konstanz, D-78457 Konstanz

We study the effects of spin-active scattering on superconductor-ferromagnet point-contact spectra using the quasiclassical theory of superconductivity. New boundary conditions for the quasiclassical Green's function allow for treating strongly spin-polarized systems with this approach. The theory describes the contact region by a general scattering matrix and various microscopic models of interfacial scattering are studied. We show that the shape of the interface potential plays a crucial role in spin-active scattering and that spin-flip processes can alter the spectra dramatically.

We show that our theory generalizes earlier models for electronic transport across such contacts based on the BTK-approach. They are contained as limiting cases in our formalism.