Electronic and Magnetic Nano Phase Separation in Cobaltates La 2 − x Sr x CoO 4

The single-layer perovskite cobaltates have attracted enormous attention due to the recent observation of hour-glass shaped magnetic excitation spectra which resemble the ones of the famous high-temperature superconducting cuprates. Here, we present an overview of our most recent studies of the spin and charge correlations in floating-zone grown cobaltate single crystals. We find that frustration and a novel kind of electronic and magnetic nano A. C. Komarek [email protected] 1 Max-Planck-Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany 2 Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22603 Hamburg, Germany 3 Laboratoire Léon Brillouin, CEA/CNRS, 91191 Gif-sur Yvette Cedex, UMR12 CEA-CNRS, Bât 563 CEA Saclay, France 4 Institute of Solid State Physics, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany 5 Institut Laue-Langevin (ILL), 6 Rue Jules Horowitz, 38043 Grenoble, France 6 Jülich Centre for Neutron Science JCNS, Forschungszentrum Jülich GmbH, Outstation at ILL, CS 20156, 71 avenue de Martyrs, 38042 Grenoble, France 7 Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM-II), TU München, Lichtenbergstr. 1, 85747 Garching, Germany 8 Georg-August-Universitát Göttingen, Institut für Physikalische Chemie, Tammannstrasse 6, 37077 Göttingen, Germany phase separation are intimately connected to the appearance of the hour-glass shaped spin excitation spectra. We also point out the difference between nano phase separation and conventional phase separation.