Analysis of the first electron-removal states of Ba2Cu3O4C12 using polarization dependent angle-resolved photoelectron spectroscopy

The first electron-removal states of the layered cuprate Ba2Cu3O4Cl2 were measured using angle-resolved photoelectron spectroscopy. The symmetry and energy-momentum relations of the lowest lying states were determined and interpreted in terms of the motion of a single hole in the two different planar Cu-O subsystems of the Cu3O4 plane. One subsystem is antiferromagnetic as in the undoped parent compounds of the high-temperature superconductors and the other is paramagnetic and corresponds to the strongly overdoped case. The data are compared to theoretical results on hole dynamics in two-dimensional antiferromagnetic or paramagnetic spin backgrounds. The lineshape, symmetry and dispersion of the first electron-removal states of Ba2Cu3O4Cl2 can be described in terms of Zhang-Rice singlets within a single band model. The photohole lifetime in the paramagnetic subsystem of the Cu3O4 plane is much smaller than with an antiferromagnetic spin background.