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R. G. Herb Condensed Matter Seminar
Spin, charge and orbital ordering in transition metal compounds: New insights obtained by resonant x-ray diffraction
Date: Thursday, September 9th
Time: 10:00 am
Place: 5310 Chamberlin
Speaker: Ioannis Zegkinoglou, Max Planck Institute for Solid State Research, Stuttgart, Germany

Many of the intriguing electronic properties exhibited by transition metal compounds with partially filled d electron orbitals originate in a competition between many-body states with different spin, orbital and charge ordering patterns. Synchrotron-based resonant x-ray diffraction (RXD) combines the unique ability to directly probe all active degrees of freedom - charge, spin and orbital - with the advantage of being element-specific. It is thus well suited for the investigation of the complex electronic states of d electron systems.

The talk will give an overview of our recent studies on 4d electron ruthenium-based oxides and 5d electron iridium-based sulfides, which were carried out using the RXD technique. In particular, we will discuss the discovery of a new orbital ordering transition between two paramagnetic phases in the layered Mott insulating system Ca2-xSrxRuO4 [1], the determination of the complex magnetic structure of its bilayered counterpart Ca3Ru2O7 [2], as well as the determination of the long-discussed magnetic structure of the superconducting magnet RuSr2GdCu2O8 [3]. The results from our ongoing, still unpublished work on the spinel compound CuIr2S4 [4] further demonstrate the power of RXD in unraveling the exciting physics of strongly correlated electron systems.


[1] I. Zegkinoglou, J. Strempfer, C.S. Nelson, J.P. Hill et al., Phys. Rev. Lett. 95, 136401 (2005)
[2] B. Bohnenbuck, I. Zegkinoglou, J. Strempfer, C. Schuessler-Langeheine, C.S. Nelson et al., Phys. Rev. B 77, 224412 (2008)
[3] B. Bohnenbuck, I. Zegkinoglou, J. Strempfer, C.S. Nelson et al., Phys. Rev. Lett. 102, 037205 (2009)
[4] I.Zegkinoglou, V. Kiryukhin, Ph. Leininger, M.W. Haverkort et al., in preparation

Host: Franz Himpsel
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