Evolution of the Electronic Structure of Y-Bi-2212 from the Antiferromagnetic to the Superconducting Regime

Abstract

The phase diagram of the cuprate superconductors at low doping and low temperatures in the non-superconducting state is dominated by magnetic correlations. When increasing the hole concentration in the CuO₂-planes from zero an antiferromagnetic (AF) insulating phase is followed for hole concentrations greater than approximately 0.08 by the superconducting phase. For the range of doping in between the situation is less clear and several models exist. For Bi₂Sr₂Y _x Ca_1−xCu₂O₈ in the range of Y-concentrations 0.9 < x < 0.0 the evolution of the electronic structure starting from the AF phase at x = 0.9, which in this respect can be regarded as the parent compound of the superconducting phase, and its gradual development into the superconducting range can be studied on one system. In this series the CuO₂-planes are kept embedded in a nearly identical environment for each hole concentration. Especially the results from the AF phase deviate from former reports attained mainly from oxychlorides.