Orbital and magnetic structure of quasi-1D cobaltites: Ab initio calculations and experiment

The magnetic properties of the orbitally degenerate quasi-one-dimensional cobaltites SrxBa1-xCoO3 are explained on the basis of a phase separation phenomenon. Noninteracting magnetic particles embedded in a nonferromagnetic matrix develop in the system. Details are given about the electronic and magnetic structure for x = 0,0.2 and 0.5. At x = 0.5, the geometry of the CoO6 trigonally distorted octahedra changes by about 1-2%, but magnetic particles get 3 times bigger, compared to the parent compound, with the corresponding changes in the magnetic properties. The electronic structure of the Co4+ ion, however, stays roughly unchanged. (c) 2005 Elsevier B.V. All rights reserved.