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 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. 
Z. W. Li, Y. Drees, A. Ricci, D. Lamago, A. Piovano, M. Rotter, W.   Schmidt, O. Sobolev, U. R\"utt, O. Gutowski, M. Sprung,...
cond-mat.str-el