High-resolution angle-resolved photoemission study of Pb-substituted Bi2201

We have performed a systematic doping-dependent angle-resolved photoemission spectroscopy (ARPES) of Pb-substituted Bi2201 (Bi 1.80Pb 0.38Sr 2.01CuO 6− δ ) with high energy (7–11 meV) and momentum (0.01 Å −1) resolutions. We found that all the samples show a large hole-like Fermi surface centered at (π,π), whose volume changes systematically as a function of doping. The superconducting gap exhibits a d x 2− y 2 -like anisotropy with a typical gap value of 10–15 meV near (π,0). By comparing with Bi 2Sr 2CaCu 2O 8 (Bi2212), we found that the size of superconducting gap is well scaled with the maximum T c ( T c max). Doping-dependence of spectral line shape at (π,0) is very similar between Bi2201 and Bi2212, while its energy scale is different by a factor of 4, corresponding to the ratio of T c max between the two compounds. These indicate that the superconducting and pseudogap properties are characterized by T c max irrespective of the number of CuO 2 layers or the BiO superstructure.