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DS: Fachverband Dünne Schichten
DS 43: Biomolecular and Functional Organic Layers II (Focused Session)
DS 43.4: Topical Talk
Freitag, 26. März 2010, 12:15–12:45, H2
Molecular orientation in phthalocyanine films assessed by combined optical and magneto-optical investigations — •Georgeta Salvan1, Michael Fronk1, Björn Bräuer1,2, Dietrich R. T. Zahn1, Oliver G. Schmidt3, and Jens Kortus4 — 1Chemnitz University of Technology, Physics Department, D-09107 Chemnitz, Germany — 2SIMES Center, SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94309, USA — 3Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, 01069 Dresden, Germany — 4TU Bergakademie Freiberg, Theoretical Physics Department, D-09596 Freiberg, Germany
Magneto-optical Kerr effect (MOKE) is commonly used to study the magnetic properties of inorganic ferromagnetic layers or magnetic nanostructures. For the example of phthalocyanine thin films it will be shown that also paramagnetic and diamagnetic molecules can exhibit a strong MOKE signal in the visible to near ultraviolet spectral range. A numerical analysis of the energy dispersion of the real and imaginary part of the complex magneto-optical Kerr rotation angle and of the optical constants allows the determination of the magneto-optical material constant, the so-called Voigt constant. For phthalocyanines this is only about two orders of magnitude smaller compared to soft ferromagnetic materials such as Ni. The magnitude of the Voigt constant is found to be highly sensitive to the orientation of the molecules with respect to the substrate plane. This opens new possibilities to accurately determine the molecular orientation in organic thin films.