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TT: Tiefe Temperaturen
TT 6: Postersitzung I (Amorphe- u. Tunnelsysteme, Niedrigdimensionale Systeme, Supraleitung: Elektronenstruktur, Phononen, Tunneln, Ordnungsparameter)
TT 6.34: Poster
Montag, 24. März 2003, 14:30–19:00, P2c, P2d
Doping dependence of the plasmon dispersion in layered cuprates and Fermi surface topology — •S.-L. Drechsler1, V..G. Grigoryan2, G. Paasch1, and H. Rosner3 — 1Leibniz-Institut f. Festkörper- und Werkstoffforschung Dresden, Germany — 2Universität des Saarlandes, Saarbrücken — 3MPI CPFS Dresden
With the assumption of either an open (h-like) or a closed (el-like) effective Fermi surface (FS) for nearly optimally doped Bi2212 two alternative effective one-electron spectra are determined applying a recently proposed general method to analyse EELS data(V.G. Grigoryan et al. Phys. Rev. B 60,1340 (1999)). Using such spectra the doping dependence of the effective FS shape and of the long-wavelength plasmon dispersion are calculated within the rigid band approximation. Whereas the closed (at optimal doping) FS remains to be closed over the whole experimentally accessible hole doping range, one finds a topological transition of the open FS (at optimal doping) to a closed FS for strong overdoping. This distinct behaviour leads to qualitatively different dependencies especially of the plasmon dispersion coefficient in [100] direction and of the anisotropy coefficient of the plasmon dispersion. It is proposed to exploit this different doping dependencies in comparison with corresponding EELS data to answer the question on the FS topology of optimally doped Bi2212 which is still under debate of recent ARPES studies. The derived open FS is in accord with recent ARPES data (A.A. Kordyuk, et al. cond-mat/0208418 (2002)). The proposed method might be helpful to determine the hole concentration. The related LDA band structure is presented and discussed.