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Unraveling electronic-structure features for metallic Na0.33CoO2 and charge-ordered Na0.5CoO2 by high-resolution electron energy-loss spectroscopy

R. J. Xiao·J. H. Chen·H. X. Yang·C. Ma·Q. Xu·H. W. Zandbergen·J. Q. Li
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Abstract

Measurements by high-resolution electron energy-loss spectroscopy (HREELS) of NaxCoO2 reveal spectral features that differ remarkably between the metallic Na0.33CoO2 and the charge-ordered insulator Na0.5CoO2. Calculations by density functional theory plus Hubbard U (DFT+U) demonstrate that these differences arise essentially from the relatively greater strength of electron correlation in addition to the crystal-field effect in Na0.5CoO2. The effective U values are estimated to be ~3.0eV for x=0.5 and ~1.0eV for x=0.33, respectively. The electronic structures for these correlation strengths give good interpretations for the physical properties observed in the materials.

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R. J. Xiao, J. H. Chen, H. X. Yang, C. Ma, Q. Xu, H. W. Zandbergen, J. Q. Li. 2006-12-07. Unraveling electronic-structure features for metallic Na0.33CoO2 and charge-ordered Na0.5CoO2 by high-resolution electron energy-loss spectroscopy. https://arxiv.org/abs/cond-mat/0612183

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