Dresden 2009 – scientific programme

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MA: Fachverband Magnetismus

MA 27: Spin Electronics / Spininjection in Heterostructures

MA 27.4: Talk

Wednesday, March 25, 2009, 17:30–17:45, HSZ 103

Study of the Spin Properties of the Organic Semiconductor CuPc doped by Alkali Metals — •Sabine Neuschwander, Jan-Peter Wüstenberg, Alexander Fischer, Mirko Cinchetti, and Martin Aeschlimann — Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, 67663 Kaiserslautern, Germany

It has been recently shown [1], that the spin-resolved two-photon photoemission (SR-2PPE) is a method allowing to collect direct experimental information about the spin properties of interfaces with OSC, such as the spin injection efficiency and the spin transport properties of OSC. Such knowledge is a fundamental prerequisite for the implementation of OSC-based spintronics devices [2]. Following the approach presented in [1], we considered the model system of a namely the heterojunction between a cobalt thin film and the OSC copper phthalocyanine (CuPc). According to [3] the electronic structure of CuPc can be modified by alkali metal doping. In particular, it is known that Cs and Na doping results in the lowering of the the energy of the unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) of CuPc. This reduction can be specifically tuned in order, to study the spin injection in the LUMO+1 state with SR-2PPE. Our results show that, resonant excitation from an occupied 3d-bulk band into the LUMO+1 gives rise to an almost 100% spin injection efficiency and to an extremely high quasi elastic spin flip length in CuPc.

[1] M. Cinchetti et al., DOI:10.1038/NMAT2334 (2008) [2] Sanvito, S., NMAT 6, 803-804 (2007) [3] H. Ding et al., APL 92,053309 (2008)