Effects of the doping and the number of planes on the shadow bands of Bi-based cuprates

Angle resolved photoemission spectroscopy (ARPES) has been used to investigate the shadow bands present at the Fermi surface of bismuth based superconductors. Bi<Subscript>2</Subscript>Sr<Subscript>2</Subscript>CaCu<Subscript>2</Subs cript>O<Subscript>8+δ</Subscript> (Bi2212) single crystals with different doping levels and Bi<Subscript>2</Subscript>Sr<Subscript>2</Subscript>CuO<Subscript>6+δ</Sub script> (Bi2201) thin films have been studied by means of momentum distribution curves along the ΓY high symmetry direction in two different Brillouin zones and for an extensive photon energy range. The results show an enhancement of the shadow band intensity in the second Brillouin zone for photon energies around hν=30 eV. Furthermore, the ratio Shadow Bands/Main Band is shown to be constant as a function of both the doping level and the number of CuO<Subscript>2</Subscript> planes. An interpretation of this observation on the basis of the current theoretical models will be provided. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2005