Produção Nacional
Electronic structure and metal-insulator transition in LaNiO 3 − δ
2002; American Physical Society; Volume: 65; Issue: 15 Linguagem: Inglês
10.1103/physrevb.65.155101
ISSN1095-3795
AutoresM. Abbate, G. Zampieri, F. Prado, A. Caneiro, J.M. González-Calbet, Maria Vallet‐Regí,
Tópico(s)Advanced Condensed Matter Physics
ResumoWe studied the changes in the electronic structure of ${\mathrm{LaNiO}}_{3\ensuremath{-}\ensuremath{\delta}}$ across the metal-insulator transition. The technique used in the study was mainly $\mathrm{O} 1s$ x-ray absorption spectroscopy (XAS). The experimental spectrum of ${\mathrm{LaNiO}}_{3.00}$ was analyzed in terms of a cluster-model calculation. The spectrum of ${\mathrm{LaNiO}}_{3.00}$ presents a sharp peak at a threshold that corresponds to ${3d}^{8}L\stackrel{\ensuremath{\rightarrow}}{̱}c̱{3d}^{9}$ transitions. Analysis of this peak indicates that the charge carriers in ${\mathrm{LaNiO}}_{3.00}$ contain considerable oxygen character. The intensity of this peak decreases in the spectrum of ${\mathrm{LaNiO}}_{2.75}$ and disappears almost completely for ${\mathrm{LaNiO}}_{2.50}.$ This suggests that the metal-insulator transition is related to the disappearance of the charge carriers and the ensuing band-gap opening. The peak in the ${\mathrm{LaNiO}}_{2.75}$ compound is split due to the presence of two nonequivalent crystallographic sites. The metal-insulator transition in this compound is tentatively attributed to potential disorder between these two sites.
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