Electronic structure and metal-insulator transition in LaNiO3Àd

M. ABBATE; G. ZAMPIERI; F. PRADO; J.M. GONZALEZ CALBET; M. VALLET REGI; A. CANEIRO

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Lugar: New York; Año: 2002 vol. 65 p. 155101 - 155109

1098-0121

We studied the changes in the electronic structure of LaNiO32d across the metal-insulator transition. Thetechnique used in the study was mainly O 1s x-ray absorption spectroscopy ~XAS!. The experimental spectrumof LaNiO3.00 was analyzed in terms of a cluster-model calculation. The spectrum of LaNiO3.00 presents asharp peak at a threshold that corresponds to 3d8LI!cI 3d9 transitions. Analysis of this peak indicates that thecharge carriers in LaNiO3.00 contain considerable oxygen character. The intensity of this peak decreases in thespectrum of LaNiO2.75 and disappears almost completely for LaNiO2.50 . This suggests that the metal-insulatortransition is related to the disappearance of the charge carriers and the ensuing band-gap opening. The peak inthe LaNiO2.75 compound is split due to the presence of two nonequivalent crystallographic sites. The metalinsulatortransition in this compound is tentatively attributed to potential disorder between these two sites.