Inverse-photoemission study of hole-concentration dependence of the electronic structure in Bi2Sr2Ca1−xYxCu2O8 (x=0.0–0.05)

Abstract

Inverse-photoemission spectroscopy has been performed on ${\mathrm{Bi}}_2$ ${\mathrm{Sr}}_2$ ${\mathrm{Ca}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Y}}_{\mathit{x}}$ ${\mathrm{Cu}}_2$ ${\mathrm{O}}_8$ ceramics, where hole concentration is controlled by the atomic ratio between divalent Ca and trivalent Y atoms. It was found that hole doping does not cause a rigid shift of the density of states relative to the Fermi level, but creates additional electronic states in the vicinity of the Fermi level.