Berlin 2012 – scientific programme
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DF: Fachverband Dielektrische Festkörper
DF 9: Poster I - Biomagnetism, FePt Nanoparticles, Magnetic Particles/Clusters, Magnetic Materials, Magnetic Semiconductors, Half-metals/Oxides, Multiferroics, Topological Insulators, Spin structures/Phase transitions, Electron theory/Computational micromagnetics, Magnetic coupling phenomena/Exchange bias, Spin-dependent transport, Spin injection/spin currents, Magnetization/Demagnetization dynamics, Magnetic measurement techniques
DF 9.34: Poster
Tuesday, March 27, 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.