J. C. Chacón-Torres, A. Y. Ganin, M. J. Rosseinsky, T. Pichler
We present a detailed in-situ Raman analysis of KC8, CaC6, and LiC6 graphite intercalation compounds (GIC) to unravel their intrinsic finger print in the Stage-1 compound. Four main components were found between 1200 cm-1 and 1700 cm-1, and each of them were assigned to a corresponding vibrational mode. From a detailed line shape analysis of the intrinsic Fano-lines of the G and D components we precisely determine the position ({\omega}ph), line width ({\Gamma}ph) and asymmetry (q) from each component (i.e. D, G, defect modulated and deintercalated G-line mode). The calculated line width and position of the G-line allow us to extract the electron-phonon coupling constant of these compounds. A coupling constant {\lambda}ph < 0.06 is obtained. This highlights that Raman active modes alone are not sufficient to explain the superconductivity within the electron- phonon coupling mechanism in CaC6 and KC8.
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http://arxiv.org/abs/1204.5971
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