Normal-state Fermi surface of pristine and Pb-doped Bi2Sr2CaCu2O8+δ from angle-resolved photoemission measurements and its photon energy independence

Abstract

We address the question as to whether the topology of the normal state Fermi surface of Bi2212 - as seen in angle resolved photoemission - depends on the photon energy used to measure it. High resolution photoemission spectra and Fermi surface maps from pristine and Pb-doped Bi2212 are presented, recorded using both polarised and unpolarised radiation of differing energies. The data show clearly that no main band crosses the Fermi surface along the GMZ direction in reciprocal space, even for a photon energy of 32 eV, thus ruling out the existence of a G-centred, electron-like Fermi surface in this archetypal high Tc superconductor. The true topology of the normal state Fermi surface remains that of hole-like barrels centred at the X,Y points of the Brillouin zone.