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TT: Fachverband Tiefe Temperaturen

TT 28: Superconductivity: Heterostructures, Andreev Scattering, Proximity Effect, Coexistence

TT 28.1: Hauptvortrag

Mittwoch, 25. März 2009, 15:15–15:45, HSZ 105

Unconventional Superconductivity induced by Interfaces and Surfaces — •Matthias Eschrig — Institut für Theoretische Festkörperphysik and DFG-Center for Functional Nanostructures, Universität Karlsruhe, D-76128 Karlsruhe, Germany

Ordered many-body states in solids are often characterized by an order parameter that breaks one or more of the symmetries of the crystal. Such unconventional states lead to interesting new physics associated with the spontaneously broken symmetries. However, in order that such a symmetry breaking can occur it has to be energetically favored. Some of the most interesting symmetry broken states have never been found experimentally in bulk materials for that reason.

However, symmetries can be broken also by introducing interfaces with other materials. In this case, the evasive unconventional states might be induced locally near the interface, and can then penetrate as correlations into bulk materials. The properties of the induced states depend on the scattering characteristics of the interfaces and on the proximity induced states produced by the adjacent materials.

We discuss in particular interface-induced unconventional superconductivity in heterostructures with magnetically active materials, that may exhibit e.g. odd-frequency pairing or equal-spin triplet pairing states. We study the conditions under which such unconventional pairing amplitudes are induced and demonstrate how they can be tested in experiment and used for quantum devices.