Polarization-dependent X-ray photoemission spectroscopy for High-Tc cuprate superconductors

We have performed photon energy ($h\nu$) and linear polarization dependent X-ray photoemission for optimal doped Pb-Bi₂Sr₂CaCu₂O_8+δ (Bi2212) to investigate the ground Cu 3d orbital symmetry. We identified that the bulk Cu 3d components in valence-band spectra develop with decreasing $h\nu$ from 7900 eV to 460 eV. Moreover, the photoelectron intensity ratio of the valence-band spectra measured at $h\nu$ = 460 eV has shown that the Cu $3d_{x^2-y^2}$ orbital contributions are dominant near the Fermi level ($E_F$). Meanwhile, we revealed that the bulk Cu $2p_{3/2}$ core-level spectra without the Bi 4s component is detected at $h\nu$ = 1550 eV compared with $h\nu$ and linear-polarization-dependent spectra.