Electronic structure and band gap of the negative charge-transfer material Sr3Fe2O7

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

SOLID STATE COMMUNICATIONS

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2004 vol. 129 p. 113 - 116

0038-1098

We studied the electronic structure of the Sr3Fe2O7 compound using X-ray photoelectron spectroscopy (XPS). The chargetransfersatellites in the Fe 2p XPS spectra were analyzed using standard cluster model calculations. The analysis indicates thatSr3Fe2O7 is in the negative charge-transfer regime, and that the ground state is dominated by the 3d5L configuration (where Ldenotes an O 2p hole in the oxygen band). These results are similar to those found in the related SrFeO3 and Sr2FeO4compounds. The band gap of the Sr3Fe2O7 compound is split off by the relatively large value of the p–d transfer integral Ts:The lowest lying excitations are 3d5L þ 3d5L!3d5 þ 3d5L2 and consequently the band gap is of the p–p type. The band gapin the Srnþ1FenO3nþ1 series can be understood taking into account the trend in the O 2p bandwidths.