Electronic structure of the negative charge-transfer material Sr3FeMO7 (M=Fe, Co, Ni)

M. ABBATE; H. ASCOLANI; L. MOGNI; F. PRADO; A. CANEIRO

PHYSICA B - CONDENSED MATTER

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2004 vol. 354 p. 7 - 10

0921-4526

We studied the electronic structure of the substituted Sr3FeMO7 compounds (M=Fe, Co, Ni). The experimentaltechnique used in the study was M 2p X-ray photoelectron spectroscopy (XPS). The charge-transfer satellites in the M2p spectra were analyzed using cluster model calculations. The analysis indicates that these materials are in the negativecharge-transfer regime, and that their ground states are dominated by the 3dn+1L configuration (where L denotes a 2phole in the oxygen band). The results are similar to those found in the closely related SrFeO3 and SrCoO3 compounds.The band gap of these compounds is split off by the relatively large value of the p–d transfer integral Ts The lowest lyingexcitations are 3dn+1L+3dn+1L-3dn+1+3dn+1L2 and the band gap is of the p–p type. The value of the p–d transferintegral Ts in the Sr3FeMO7 compounds decreases from Fe to Ni. In turn, this helps to explain the increase in theelectrical conductivity along the M=Fe, Co, Ni series.