Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 22: Spin Dynamics / Spin Torque III

MA 22.1: Hauptvortrag

Donnerstag, 25. März 2010, 09:30–10:00, H10

Tailoring the spin functionality of a hybrid metal-organic interface by means of alkali metal doping — •Mirko Cinchetti, Sabine Neuschwander, Jan-Peter Wüstenberg, Alexander Fischer, and Martin Aeschlimann — Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, 67663 Kaiserslautern, Germany

Doping of organic semiconductors (OSCs) has proven to be an efficient strategy to adjust their electronic properties for implementation in organic-based electronic devices. The recent success in the application of OSCs for spintronics raises the fundamental question if doping can be used as well to tailor the functionality of hybrid metal-organic interfaces, and thus to control the high spin injection efficiency achievable in OSC. We employ a recently developed purpose-made technique based on spin resolved two-photon photoemission spectroscopy [1] to study the influence of alkali doping (Cs and Na) on the spin functionality of the interface between a thin cobalt film and the organic semiconductor copper phthalocyanine (CuPc). We find two alkali-induced effects. First, alkali atoms act as impurities and increase the spin-flip probability for the electrons crossing the interface (detrimental effect). Second, they allow to enhance the efficiency of spin-injection at an arbitrary energy above the Fermi level of the cobalt (intrinsic effect). We show that the intrinsic effect dominates over the detrimental one, giving rise to the possibility to actively tailor the spin functionality of the considered hybrid interface by changing the doping concentration.

[1] M. Cinchetti et al., Nature Materials 8, 115-119 (2009)