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Fermi Surface Topology And Angle-Resolved Photoemission Results Of Bi2212 Syngle Crystals

M.C. Asensio

LURE, Centre Universitaire Paris Sud, Bât 209D . 91898 Orsay, France &
Instituto de Ciencia de Materiales, CSIC, 28049 Madrid, Spain.

Angle-resolved photoemission (ARPES) has been a useful tool to study single particle properties of high-Tc superconducting materials [1].
There are two main approaches of ARPES that are used to study the Fermi surface features of the high-Tc superconductors. The traditional method is based on the measurement of energy distribution curves (EDC) in all high-symmetry directions of the Brillouin zone (BZ) in order to determine the reciprocal space localization of the Fermi level crossing of the quasi-particle bands. The second approach is based on measuring the photointensity within a narrow energy window at the Fermi level (Ef) defined by the spectrometer and photon source resolution to get the distribution of spectral weight near the Fermi level in the k space. This second approach has the advantage that it provides a global view of the topology of the Fermi surface throughout the whole BZ. However, the photointensity images are influenced by strong matrix elements which depend on the angle between the polarization vector of the photon beam and the wave vectors of the initial and final state involved in the photoemission process [2].

We report on recent photoemission data of the normal state of Bi2212 compounds (Tc = 91 K) recorded using  high-resolution synchrotron radiation ARPES at LURE. As a function of the incident photon energy, we have performed complete scans of the BZ in two different polarization geometry detections. Particular attention has been paid to the current controversy on whether or not the Fermi surface is electron- or hole-like in the vicinity of the M( ,0) high symmetry point. By mapping the spectral weight in the momentum space, we have found substantial additional information concerning the symmetry of those initial states that define the Fermi surface contours. The completeness of our results provides a clear identification of the key features associated to the Fermi surface of the Bi-based high Tc superconductors.

References
[1]     Z.-X. Shen, W.E. Spicer, D.M. King, D.S. Desseau, and B.O.Wells, Science 267, 343 (1995); Z.-X. Shen and D.S. Desseau, Phys. Rep. 253, 1(1995) and references therein.
[2]     A. Bansil and M. Lindroos, Phys. Rev. Lett., 83, 5154(1999).


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