ANGLE-RESOLVED-PHOTOEMISSION STUDY OF BI2SR2CACU2O8+DELTA - METALLICITY OF THE BI-O PLANE

We have performed high-resolution angle-resolved-photoemission experiments on Bi2Sr2CaCu2O8+single crystals with different annealing histories. By depositing a small amount of Au on the surface, we were able to distinguish electronic states associated with the Bi-O surface layer. We found that the Bi-O atomic surface layer is metallic and superconducting for samples that were high-temperature annealed in oxygen but not for as-grown samples. The Cu-O plane is found to be superconducting in all samples. © 1990 The American Physical Society.