Local magnetic properties and spin state of YBaCo2O5.5:: 59Co NMR study

Co-59 NMR studies have been made to clarify the spin state and local magnetic properties of YBaCo2O5.5, a new cobalt oxide with an oxygen-deficient and A-site ordered perovskite structure. In the antiferromagnetic state we observed four Co NMR spectra with internal fields of 216, 24, 19, and 0 kOe. This means that the crystal structure at low temperatures does not have the 2 x 1 x 1 superstructure observed at room temperature. (C) 2003 Elsevier Science B.V. All rights reserved.