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HL: Fachverband Halbleiterphysik

HL 71: Poster Session: Graphene / Topological Insulators / Interfaces and Surfaces

HL 71.5: Poster

Mittwoch, 28. März 2012, 16:00–19:00, Poster D

Non-local Andreev reflection as a probe of spin entanglement in graphene nanostructures — •Hans Hettmansperger¹, Patrik Recher², and Björn Trauzettel¹ — ¹Institute for Theoretical Physics and Astrophysics, University of Würzburg, 97074 Würzburg, Germany — ²Institute for Mathematical Physics, TU Braunschweig, 38106 Braunschweig, Germany

The controlled production and detection of spin-entangled electronic states without the use of ferromagnetic reservoirs is a major challenge in solid state physics. Non-local Cooper pair injection from ordinary superconductors into graphene nanostructures can be used to generate spin entanglement. The advantage of graphene is twofold: (i) spin is long-lived in graphene because it only weakly couples to the environment; (ii) graphene nanoribbons have specific properties that allow for a spin detection in the absence of ferromagnetic reservoirs.

In our numerical analysis, we solve the Bogoliubov-de Gennes equation for the tight binding model of graphene by applying the recursive Green's functions method for phase-coherent transport to multi-terminal devices. We study the average current and the current noise within and between different electron reservoirs and identify ideal situations to generate and detect spin entanglement. To do so, we employ graphene-specific physics such as valley filtering and magnetic ordering due to electron-electron interactions in zigzag nanoribbons.