Dresden 2009 – scientific programme

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MA: Fachverband Magnetismus

MA 23: Magnetic Thin Films II

MA 23.9: Talk

Wednesday, March 25, 2009, 16:45–17:00, HSZ 04

Magneto-optical properties of organic/ferromagnetic bilayers — •Wen Li, Michael Fronk, and Georgeta Salvan — Physics Department, Chemnitz University of Technology, D-09107 Chemnitz

The magneto-optical Kerr effect (MOKE) of organic/ferromagnetic bilayers consisting of rubrene on top of nickel layers or vice versa was measured spectroscopically resolved in the energy range from 1.5 eV to 5.5 eV. In the MOKE hysteresis recorded at room temperature at fixed wavelength the heterostructures exhibit a superparamagnetic superimposed on a ferromagnetic behaviour. The MOKE spectra of the heterostructures were simulated using a multi-layer model that takes into account the dielectric functions of the organic layer and Ni as well as the Voigt constant of Ni. To improve the match to the experimental spectra, the film thicknesses were adjusted and a gradient in their optical properties was implemented in the simulation. From the comparison between the simulated and the experimental spectra conclusions are drawn regarding the structure of the bilayers. When the rubrene is deposited onto Ni the rubrene film oxidizes upon exposure to atmosphere with the formation of rubrene peroxide. The growth of Ni on top of the rubrene layer has a capping effect preserving the oxidation of the rubrene underlayer.