Berlin 2008 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 18: Correlated Electrons: Low-dimensional Systems - Materials 2

TT 18.5: Vortrag

Dienstag, 26. Februar 2008, 16:15–16:30, H 2053

Electron-phonon interaction in the lamellar cobaltate Na_xCoO₂ — •Alexander Donkov¹, Maxim Korshunov^1,2, and Ilya Eremin^1,3 — ¹Max-Planck-Institut für Physik komplexer Systeme, D-01187 Dresden, Germany — ²L.V. Kirensky Institute of Physics, Siberian Branch of Russian Academy of Sciences, 660036 Krasnoyarsk, Russia — ³Institute für Mathematische und Theoretische Physik, TU Braunschweig, D-38106 Braunschweig, Germany

We study theoretically the dependence of the electron-phonon interaction in Na_xCoO₂ on the sodium concentration, x. For the two 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, ω, 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.

M.K. acknowledges support from INTAS (YS Grant 05-109-4891) and RFBR(Grants 06-02-16100, 06-02-90537-BNTS).