Dresden 2009 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 27: Spin Electronics / Spininjection in Heterostructures
MA 27.3: Vortrag
Mittwoch, 25. März 2009, 17:15–17:30, HSZ 103
Determination of spin injection and transport in a ferromagnet/organic semiconductor heterojunction by two-photon photoemission — •Mirko Cinchetti1, Kathrin Heimer1, Jan-Peter Wüstenberg1, Oleksiy Andreyev2, Michael Bauer2, Stefan Lach1, Christiane Ziegler1, Yongli Gao3, and Martin Aeschlimann1 — 1University of Kaiserslautern, Germany — 2Universität Kiel, Germany — 3University of Rochester, USA
A fundamental prerequisite for the implementation of organic semiconductors (OSC) in spintronics devices is the still missing basic knowledge about spin injection and transport in OSC. Here, we consider a model system consisting of a high-quality interface between the ferromagnet cobalt and the OSC copper phthalocyanine (CuPc) [1]. We focus on interfacial effects on spin-injection and on the spin transport properties of CuPc. Using spin-resolved two-photon photoemission we have measured directly and in-situ the efficiency of spin injection at the cobalt/CuPc interface. We report a spin injection efficiency of 85%-90% for injection into unoccupied molecular orbitals of CuPc. Moreover, we estimate an electron inelastic mean free path in CuPc in the range of 1nm and a much higher quasi-elastic spin-flip length. We demonstrate that quasi-elastic spin-flip processes with energy loss smaller than 200 meV are the dominant microscopic mechanism limiting the spin diffusion length in CuPc.
[1] M. Cinchetti et al., Nature Materials, DOI:10.1038/NMAT2334