Abstract
Co K-edge X-ray absorption near-edge spectra at 300 K and magnetic studies for the rhombohedral LaCoO 3 with low-spin state to intermediate-spin (IS) state transition T s ≃105 K and orthorhombic EuCoO 3 (T s ≃295 K) are reported. The small pre-edge feature observed is from 1s-3d dipole transition, which is weakly allowed through the hybridization of Co 4p states with 3d states of neighboring Co atoms. For both samples in the IS state, pre-edge can be fitted using three peaks with energy separation P 2 - P 1 = 2.0 eV for R = La and Eu, and P 3 - P 2 = 1.5 eV for R = La and 1.3 eV for R = Eu. Since the thermally excited IS state is a mixed t 2g 5 e g 1 and d 7 L (t 2g 6 e g 1 or t 2g 5 e g 2 ), with almost filled t 2g↑ states. From reported band structure calculation, the three peaks P 1 , P 2 , P 3 are probably corresponding to the unfilled t 2g↓ , e g↑ and e g↓ states, respectively. © 2003 Elsevier Science B.V. All rights reserved.