We report topology of the Fermi surface of Bi2Sr2CaCu2O8+delta superconducting system at the optimum doping determined by sequential angle-scanning photoemission combined with high intensity of synchrotron radiation. The Fermi surface at the optimum doping has a pseudogap around (pi, 0) as in underdoped samples, showing missing segments near the M points, and shadow bands around (0.5 pi, 0.5 pi) and equivalent locations. The k dependence of the pseudogap shows a particular asymmetric topology that imposes a strong constraint on its theoretical explanation.
Topology of the pseudogap and shadow bands in Bi2Sr2CaCu2O8+d at optimum doping / Saini, Naurang Lal; J., Avila; Bianconi, Antonio; A., Lanzara; M. C., Asenzio; S., Tajima; G. D., Gu; N., Koshizuka. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 79:(1997), pp. 3467-3470. [10.1103/PhysRevLett.79.3467]