Dresden 2009 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 6: Postersession Correlated Electrons: (General) Theory, Low-Dimensional Systems, Kondo Physics, Heavy Fermions, Quantum-Critical Phenomena

TT 6.16: Poster

Montag, 23. März 2009, 13:00–16:45, P1A

Electronic properties of Fe, Mn, and Ni impurities in MgO thin films — T. Haupricht¹, •Y.-Y. Chin^1,2, R. Gierth¹, J. Weinen¹, S. G. Altendorf¹, A. Hendricks¹, Z. Hu¹, J. Gegner¹, H. Fujiwara¹, D. Regesch¹, H. H. Hsieh³, H.-J. Lin², C. T. Chen², and L. H. Tjeng¹ — ¹Institute of Physics II, University of Cologne, Germany — ²National Synchrotron Radiation Research Center, Hsinchu, Taiwan — ³Chung Cheng Institute of Technology, National Defense University, Taoyuan, Taiwan

Transition metal ions in MgO can serve as model systems for various (usually more complicated) dⁿ systems in octahedral symmetry. Going from bulk crystals to impurity systems the core level and valence band photoemission (PES) and soft x-ray absorption (XAS) spectra can change significantly e.g. due to the absence of non-local screening effects [v. Veenendaal et al., PRL 70 (1993)]. Here, we present our core level and valence band PES and XAS data of Fe, Mn, and Ni impurities in MgO thin films grown on metal substrates in-situ by means of molecular beam epitaxy (MBE). Compared to the bulk compounds FeO, MnO, and NiO, remarkable differences are observed in the spectra. In order to understand these differences we have simulated the spectra using configuration interaction cluster calculations. Ab-initio oriented approaches such as LDA+DMFT are highly desired to obtain parameter free explanations.