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TT: Fachverband Tiefe Temperaturen

TT 54: SC: Heterostructures, Andreev Scattering, Proximity Effect

TT 54.2: Talk

Thursday, March 17, 2011, 15:45–16:00, HSZ 301

Nonlocal conductance via overlapping Andreev bound states in ferromagnet-superconductor heterostructures — •Georgo Metalidis¹, Matthias Eschrig^1,2, Roland Grein¹, and Gerd Schön¹ — ¹Institut für Theoretische Festkörperphysik and DFG-Center for Functional Nanostructures, Karlsruher Institut für Technologie, D-76128 Karlsruhe, Germany — ²Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany

In a setup where two ferromagnetic electrodes are attached to a superconductor, Andreev bound states are induced at both ferromagnet/superconductor interfaces. We study how these states propagate through the superconductor and interact with each other. We find that the energetic positions of the Andreev states are not anymore determined solely by the magnetic properties of a single interface, but depend on the interface distance and the relative magnetization orientation of the ferromagnetic contacts as well. These bound states show up as distinct peaks in the nonlocal conductance signal and lead to marked asymmetries with respect to the applied voltage. Our results are related to nonlocal crossed Andreev and elastic co-tunneling processes.