X-ray absorption of the negative charge-transfer material SrFe1-xCoxO3 -: art. no. 165120

We studied the relation between the electronic structure and the phsyiscal properties of SrFe1-xCoxO3. The main technique used in the study was Fe 2p, Co 2p, and O 1s x-ray absorption spectroscopy. The experimental spectra were analyzed in terms of the configuration-interaction cluster model calculation. The analysis of the spectra shows that both SrFeO3 and SrCoO3 are in the negative-charge transfer regime (this means that their ground states are mostly covalent and contain considerable O 2p hole character). SrFeO3 is in a high-spin state and SrCoO3 in an intermediate-spin state stabilized by strong hybridization. The local electronic structure and the corresponding spin state are mostly preserved in SrFe1-xCoxO3. The relatively large O 2p hole weight in the ground state explains the absence of Jahn-Teller distortions, as well as the relatively large value of the magnetic moment observed at the O sites in these materials. SrFe1-x CoxO3 illustrates both ferromagnetism and magneto-resistance in a negative charge-transfer material.