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Experimental and theoretical investigations of the electronic and magnetic coupling of iron and copper phthalocyanine to ferromagnetic Co(100) surfaces |
Christiane Ziegler 1, Stefan Lach 1, Felix Schmitt 1, Jens Sauther 1, Ehesan Ali 2, Peter M. Oppeneer 2 |
1. University of Kaiserslautern (TU-KL), Gottlieb-Daimler-Strasse, Kaiserslautern 67663, Germany |
Abstract |
Organic semiconductors with an open shell structure at the central metal atom are known to show promising magnetic properties, advertising them for use in organic spintronics [1]. For the reported investigations thin films of copper (CuPc) and iron phthalocyanine (FePc) on ultra thin layers of Co(100) were utilized. The investigation of the electronic interaction was performed by means of photoelectron spectroscopy (XPS, UPS and IPES). XPS reveals interactions between the pyrolic nitrogen atoms and Co which are different for the two Pcs. The analysis of the multiplet structures appearing for the nitrogen core levels in the submonolayer regime indicates a stronger electronic coupling of FePc to the Co surface as in the case of CuPc. UPS investigations of the valence band electronic structure with a detailed analysis of the Co dominated region near the Fermi level, indicate a rehybridization for both molecules in the sub monolayer regime. In order to clarify the influence of the two different central atoms on the electronic and the magnetic coupling to the Co substrate, theoretical calculations were performed. DFT+U calculations with a Coulomb U term [2] using a structure of Fe/Cu-Pc adsorbed on a 3-layered Co surface indicate a distinctly stronger interaction for FePc, corroborating the spectroscopic data. Ferromagnetic coupling between FePc and Co is favored over an antiferromagnetic coupling. Comparing the theoretically found local density of states for the two different organic/inorganic hybrid systems, the spectroscopically detected features near the Fermi level will be discussed in terms of different rehybridization mechanisms depending on the nature of the central metal. [1] M. Cinchetti, K. Heimer, J. P. Wüstenberg, O. Andreyev, M. Bauer, S. Lach, Ch. Ziegler, Y. Gao, M. Aeschlimann, Nature Mat., 8 ,115 (2009) [2] P.M. Oppeneer, P.M. Panchmatia, B. Sanyal, O. Eriksson and Md. E.Ali, Progress in Surf. Science, 84, 18, (2009) |
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Presentation: Oral at E-MRS Fall Meeting 2009, Symposium E, by Christiane ZieglerSee On-line Journal of E-MRS Fall Meeting 2009 Submitted: 2009-05-11 12:34 Revised: 2009-06-07 00:48 |