Plasmon dispersion and broadening in A3C60 (A=K, Rb).

Gunnarsson O., Liechtenstein A.I., Eyert V., Knupfer M., Fink J., Armbruster J.F.

Inelastic electron energy loss measurements of the 0.5-eV charge carrier plasmon in K3C60 are presented, showing that the plasmon has a very large broadening but a negligible dispersion. The response function is calculated in a self-consistent, conserving approximation, showing that the plasmon broadening can be explained in terms of a decay in an electron-hole pair dressed by phonons. The plasmon dispersion can be understood within the random-phase approximation. Local-field effects tend to give a large negative dispersion, which is compensated by interband effects.

Physical Review B, 53 3455-8, 1996.

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