Spin-glass state induced by cobalt substitution in CaRuO3

This paper reports on an experimental study of the effects induced by the substitution of Co for Ru in CaRuO3, a prototypical oxide close to a magnetic instability. The L-2,L-3 x-ray absorption spectroscopy (XAS) spectra of Ru and Co in CaRu1-xCoxO3 reveal that Co is in a divalent state for low x values, while the Ru valence increases upon increasing the Co content. The dc and ac magnetic susceptibilities demonstrate that the CaRu(1-x)CoxO(3) compounds can be classified as spin glasses. The origin of this behaviour and its implications are discussed. The effect of Co is also compared with the literature about substitutions by other cations in the magnetic sublattice of CaRuO3.