Spin-dependent trapping of electrons at spinterfaces

By S. Steil, N. Großmann, M. Laux, A. Ruffing, D. Steil, M. Wiesenmayer, S. Mathias, O. Monti, M. Cinchetti, M. Aeschlimann. Nature Physics, 2013

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Hybrid ferromagnetic metal/organic interfaces—also known as spinterfaces—can exhibit highly efficient spin-filtering properties and therefore present a promising class of materials for the future development of new spintronic devices. Advancing the field depends critically on elucidating the fundamental microscopic processes that eventually determine the spin-filtering properties in such hybrid structures. Here, we study the femtosecond spin dynamics at the prototypical interface between cobalt and the metalorganic complex tris(8-hydroxyquinolinato)aluminium. To disentangle the microscopic origin of spin filtering, we optically generate a transient spin polarization in a well-defined hybrid interface state that we follow with a spin-resolved real-time pump–probe two-photon photoemission experiment. We find that the electrons are trapped at the interface in a spin-dependent manner for a surprisingly long time of the order of 0.5–1 ps. We conclude that ferromagnetic metal/organic interfaces act as spin filters because electrons are trapped in hybrid interface states by spin-dependent confining potentials. Understanding the origin of spin filtering in metal/organic interfaces is important for the control of spin injection in organic semiconductors. A time-resolved photoemission experiment shows that spin filtering can be explained by the trapping of electrons in spin-dependent potentials at the interface.

Subfields: Atomic and Molecular Physics, and Optics, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/45faa5dc0412f625fa13b253c183cde62819447e