Regensburg 2010 – wissenschaftliches Programm
DS 8.13: Vortrag
Montag, 22. März 2010, 17:15–17:30, H3
Electronic structure, magnetic and dielectric properties of the edge-sharing copper-oxide chain compound NaCu2O2 — •Philippe Leininger1, Martin Rahlenbeck1, Markus Raichle1, Britta Bohnenbuck1, Andrey Malyuk2, Chengtian Lin1, Bernhard Keimer1, Eugen Weschke2, Enrico Schierle2, Shinichiro Seki3, Yoshi Tokura3, and John Freeland4 — 1Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, D-70569 Stuttgart, Germany — 2Helmholtz-Zentrum Berlin für Materialien und Energie, D-12489 Berlin, Germany — 3University of Tokyo, Dept. of Applied Physics, Bunkyo-ku, Tokyo 113-8656, Japan — 4Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA
We report an experimental study of NaCu2O2, a Mott insulator containing chains of edge-sharing CuO4 plaquettes, by polarized x-ray absorption spectroscopy (XAS), resonant magnetic x-ray scattering (RMXS), magnetic susceptibility, and pyroelectric current measurements. The XAS data show that the valence holes reside exclusively on the Cu2+ sites within the copper-oxide spin chains and populate a d-orbital polarized within the CuO4 plaquettes. Our results also demonstrate a new orbital selection rule for RMXS that is of general relevance for magnetic structure determinations by this technique. Dielectric property measurements reveal the absence of significant ferroelectric polarization below TN, which is in striking contrast to corresponding observations on the isostructural compound LiCu2O2. The results are discussed in the context of current theories of multiferroicity.
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