Year: 2007
Type: article
Abstract: The effect of surface degradation of the thermolectric cobaltite on Raman spectra is discussed and compared to experimental results from ${\mathrm{Co}}_{3}{\mathrm{O}}_{4}$ single crystals. We conclude that on NaCl-flux grown ${\mathrm{Na}}_{x}\mathrm{Co}{\mathrm{O}}_{2}$ crystals a surface layer of ${\mathrm{Co}}_{3}{\mathrm{O}}_{4}$ easily forms that leads to the observation of an intense phonon around $700\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$ [Y. G. Shi et al., Phys. Rev. B 70, 052502 (2004)]. The Raman spectra on freshly cleaved crystals from optical floating zone ovens do not show such effects and have a high-frequency phonon cutoff at approximately $600\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$ [P. Lemmens et al., Phys. Rev. Lett. 96, 167204 (2006)]. We discuss the relation of structural dimensionality, electronic correlations, and the high-frequency phonon cutoff of the thermolectric cobaltite.
Source: Physical Review B
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W1668155608