EPR study of spin-state transition in LaCoO3

In order to investigate the spin-state transition of cobalt ions in LaCoO3, susceptibility and Gd3+-EPR were measured for the single-crystals LaCoO3 a nd La(1 %Gd)CoO3, respectively. Below 80 K, the seven lines due to the crys tal field of Gd3+EPR can be observed. The crystal field parameter D was cal culated as a function of T. Above 40 K, the parameter D and the line width AHpp of the main peak increase while the resonance field H-x decreases. The se results indicate a transition to Co3+ excited spin-state above about 40 K, which involves local ion-distortion. (C) 2001 Elsevier Science B.V. All rights reserved.