Berlin 2012 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 19: Poster I: Multiferroics (jointly with MA, DF, KR, TT), Spins in organic materials (jointly with MA), FePt Nanoparticles (jointly with MA, MM)

DS 19.34: Poster

Dienstag, 27. März 2012, 12:15–15:15, Poster A

XAS and XMCD of ultrathin Fe layers on BaTiO₃(001): Experiment and Theory — •Stephan Borek¹, Angelika Chassé¹, Guntram Fischer¹, Wolfram Hergert¹, Remya Kunjuvettil Govind¹, Karl-Michael Schindler¹, Vasili Hari Babu², Joachim Gräfe², Martin Welke², and Reinhard Denecke² — ¹Institut für Physik, Martin-Luther-Universität Halle-Wittenberg — ²Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig

Promising candidates for switching the magnetization using voltages are multiferroic systems. As a model system we studied ultrathin Fe layers on BaTiO₃(001). Using x-ray absorption spectroscopy as a powerful method to investigate structural, electronic and magnetic properties simultaneously, the circular dichroism in x-ray absorption (XMCD) and x-ray absorption as such were used to determine the remanent magnetization as a function of film thickness. The onset of ferromagnetism at a temperature of 150 K was found for 5±1 layers. Using a Heisenberg-model in the framework of Monte-Carlo-Simulations shows that up to 3 monolayers the critical temperature is around 170 K. In addition the contribution of each layer could be separated using a fully relativistic multiple scattering formalism. Different magnetic structures and their impact on the spectroscopic properties, as well as the anisotropic behaviour of the multiferrroic systems have been investigated theoretically. The spin and orbital moments as obtained from the XMCD experiments and DMFT calculations will be compared.