Angle-resolved photoemission on untwinned $\mathrmYBa_2\mathrmCu_3\mathrmO_6.95.$ II. Determination of Fermi surfaces
We present complete Fermi-surface mappings of an untwinned single crystal of YBa2Cu3O7-δ in two distinct photon polarization geometries. Various methods for Fermi-surface determination with angle-resolved photoelectron spectroscopy are discussed and a technique based on the momentum space density of states is developed and applied. The data reveal the presence of two CuO2 plane-derived Fermi-surface pockets, along with weak evidence for a single chain sheet, in agreement with earlier work on twinned crystals and ab initio predictions, but show no sign of the expected “stick” pocket centered at (π,π). In contrast with earlier work on Bi2Sr2CaCu2O8+δ, we see no evidence for “shadow bands” in optimally doped YBa2Cu3O7-δ, supporting the contention that these features arise from structural rather than magnetic correlations.