Photoemission study of the high-T_c superconductor Bi_1.8Pb_0.4Sr₂Ca_2.2Cu₃O₁₀

Abstract

Ultraviolet and X-ray photoemission spectroscopic (UPS and XPS) studies to characterize the electronic structure of bismuth cuprate superconductor with nominal composition of Bi_1.8Pb_0.4Sr₂Ca_2.2Cu₃O₁₀ have been carried out. The data clearly shows the metallic emission at the Fermi level (E_F). The shoulder (-1.2 eV) near the E_F is attributed to the Cu-O derived states. Cu satellite structures observed both in the UPS and XPS show the strongly correlated nature of the Cu 3d electrons. Core level shifts indicate that 3+ and 4+ are the main oxidation of Bi and Pb, respectively. The Pb core lines show two components indicating their inequivalent sites. Core level O 1s spectrum is deconvoluted to show the presence of structurally non-equivalent oxygen sites.