Electron-phonon interaction in the lamellar cobaltate Na${}_x$CoO${}_2$

Abstract

We study theoretically and experimentally the dependence of the electron-phonon interaction in Na${}_x$CoO${}_2$ on the sodium concentration $x$. For the two oxygen phonon modes found in Raman experiments, $A_{1g}$ and $E_{1g}$, we calculate the matrix elements of the electron-phonon interaction. Analyzing the feedback effect of the conduction electrons on the phonon frequency we compare the calculated and experimentally observed doping dependence of the $A_{1g}$ mode. Furthermore, due to the momentum dependence of the electron-phonon coupling for the $E_{1g}$ symmetry we find no renormalization of the corresponding phonon frequency which agrees with experiment. Our results shed light on the possible importance of the electron-phonon interaction in this system.

5 pages, 2 figures (submitted to PRB)

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Cited by in corpus (1)

• Rearrangement of Sodium ordering and its effect on physical properties in $N{a}_{x}Co{O}_2$ system