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O: Fachverband Oberflächenphysik

O 60: Focussed Session: Organic Materials for Spintronics: From Spinterface to Devices (jointly with DS, HL, and MA)

O 60.3: Topical Talk

Donnerstag, 14. März 2013, 10:30–11:00, H32

Magneto-optical Kerr Effect Spectroscopy of Selected Phthalocyanines and Porphyrines — •Georgeta Salvan¹, Peter Robaschick¹, Frank Lungwitz¹, Michael Fronk¹, Carola Mende¹, Heinrich Lang¹, Rico Friedrich², Jens Kortus², and Dietrich R.T. Zahn¹ — ¹TU Chemnitz, 09126 Chemnitz, Germany — ²2TU Bergakademie Freiberg, Freiberg 09596, Germany

Phthalocyanines and porphyrines find nowadays many applications from pigments to organic electronics. Nevertheless, they still have a special charm for fundamental investigations thanks to the large flexibility of their molecular structure. This work focuses on the influence of the molecular spin ground state on the room temperature magneto-optical activity of some phthalocyanines and porphyrins. The films in the typical thickness range between 30 nm and 100 nm were prepared by organic molecular beam deposition in high vacuum. Magneto-optical Kerr effect (MOKE), which is commonly used to study the magnetic properties of inorganic ferromagnetic layers or magnetic nanostructures, is measured here spectroscopically in the region of the Q and B absorption bands of phthalocyanines and porphyrines. From this the magneto-optical Voigt constant is calculated numerically and can be correlated to the electronic properties of the molecules. For instance, the hybridisation of Co3d states with the HOMO π-orbital of CoPc leads to additional features in the magneto-optical spectra compared to e.g. CuPc. The magnitude of the Voigt constant in the Q band is hardly sensitive to the molecular spin, but highly sensitive to the orientation of the molecules with respect to the substrate plane.