Dresden 2003 – wissenschaftliches Programm
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MA: Magnetismus
MA 14: Poster: Schichten(1-31), Spinabh.Trsp.(32-47), Exch.Bias(48-54), Spindyn.(55-64), Mikromag.(65-76), Partikel(77-88), Oflmag.(89-92), Spinelektr.(93-98), Elektr.Theo.(99-103), Mikromag+PhasÜ+Aniso.(104-122), MagnMat.(123-134), Messm+Mol-Mag.(135-139), Kondo(140-151)
MA 14.152: Poster
Dienstag, 25. März 2003, 15:15–19:15, Zelt
Charge and magnetic order in copper oxide chain compounds — •Lucia Capogna1, Bernhard Keimer1, Michael Sofin1, Martin Jansen1, and Alexander Ivanov2 — 1Max Planck Institute for Solid State Research, Heisenbergstrasse 1 - 70569 Stuttgart - Germany — 2Institut Laue-Langevin, 6 rue Jules Horowitz BP 156 - 38042 Grenoble Cedex 9 - France
Transition metal oxides have been the focus of intense research over the past two decades and charge order has been one of the pervasive themes. For instance, a competition between charge ordered insulating and metallic states with itinerant charge carriers gives rise to the phenomenon of colossal magnetoresistance in manganese oxides and charge order in the form of stripes has played a prominent role in research on copper oxide high temperature superconductors.
Recently, a novel class of copper oxide compounds whose Cu2+/Cu3+ ratio can be accurately tuned has been synthetised at the MPI Stuttgart. The backbone of their lattice structure is a single set of CuO2 chains made up of CuO4 squares in an edge-sharing fashion: no other electronically active element is present. As a first step towards a characterisation of the interplay between charge and magnetic order, we have investigated the magnetic structure of three members of the series: NaCu2O2, Na3Cu2O4 and Na8Cu5O10. The Cu2+/Cu3+ ratios in these compounds are 1:0, 1:1 and 3:2 respectively. Sharply defined superstructures of alternating Cu2+ and Cu3+ ions are observed in Na3Cu2O4 and Na8Cu5O10 even at room temperature whilst antiferromagnetic sets in at low temperatures.