Berlin 2008 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 18: Poster: Towards Molecular Spintronics, Organic Thin Films, Optical Layers, Vibrational Spectroscopy, Tayloring organic interfaces

DS 18.8: Poster

Dienstag, 26. Februar 2008, 14:30–19:30, Poster A

Spectroscopic determination of the Voigt constant of copper phthalocyanine by magneto-optical Kerr effect and ellipsometry investigations — •Michael Fronk, Dietrich R.T. Zahn, and Georgeta Salvan — Physics Department, Chemnitz University of technology, D-09107 Chemnitz

The measurement of the magneto-optical Kerr effect (MOKE) is frequently used to monitor magnetic properties of ferromagnetic thin films during growth (e.g. [1]). MOKE spectroscopy can also be employed to determine the Voigt constant of ferromagnetic layers [2,3], if the optical constants of the involved layers are known. In this work the Voigt constant of copper phthalocyanine (CuPc) is calculated using the experimental results of polar MOKE spectroscopy and variable angle spectroscopic ellipsometry (VASE) investigations. The calculations were carried out using a three layer model air - film - substrate for normal incidence and considering the decomposition of the linearly polarised incident light into its two circularly polarised eigenmodes. The CuPc films were grown by organic molecular beam deposition in high vacuum onto silicon substrates either H-passivated or covered by native oxide. When deposited on silicon with native oxide the molecules adopt a close to standing orientation, while those grown on H-passivated substrates align with an average tilt angle of about 55° with respect to the substrate plane. This leads to significant differences in the magnitude of the Voigt constants of CuPc on the two types of substrates.

[1] M. Wahl et al., phys. stat. sol. (c) 0, 2003, 3002 [2] T. Herrmann et al., PRB 73, 2006, 134408 [3] J. Zak et al., PRB 43, 1991, 6423