2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/24520In this paper we summarize our STM studies of the density of electronic states in nearly optimally doped Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$ in zero field. We report on the inhomogeneity of the gap structure, density of states modulations with four-lattice constant period, and coherence peak modulation.Presented at SNS'2004, Sitges,Spain, July 11-16,2004, being considered for publication in J. Phys. Chem. SolidsSuperconductivityStrongly Correlated Electronstext