G. ZAMPIERI; F. PRADO; A. CANEIRO; J. BRIÁTICO; M.T. CAUSA; M. TOVAR; B. ALASCIO; M. ABBATE; E. MORIKAWA

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Lugar: New York; Año: 1998 vol. 58 p. 3755 - 3761

1098-0121

We studied the electronic structure of CaMnOx (2.66<x<3.00) using x-ray photoemission and O 1s x-rayabsorptionspectroscopy. Analyzing the spectra of the two end members with the configuration-interactioncluster model, we have determined all the main parameters of the electronic structure. We have found that theground states of CaMnO2.5 and CaMnO3 are highly covalent, with approximately the same number of ligandholes per oxygen atom: 0.22–0.23. The main separations between the Mn 3d bands closest to the Fermi levelare of the order of 3 eV and the band gaps are of the charge-transfer type (U.D). The main effects of theoxygenation are the disappearance of the occupied eg" band and an approximately rigid shift of about 1 eV tolower energies of all the other Mn 3d bands. Finally, we discuss the most probable causes for the absence ofa metallic phase in CaMnOx .