Systematics of the Photoemission Spectral Function of Cuprates: Insulators and Hole- and Electron-Doped Superconductors

Angle-resolved photoemission studies on ${\mathrm{Sr}}_{2}{\mathrm{CuO}}_{2}{\mathrm{Cl}}_{2}$ at a temperature below its N\'eel temperature reveal detailed momentum dependent line shape changes as a function of wave vector. While a sharp quasiparticlelike peak is observed near ( $\ensuremath{\pi}/2,\ensuremath{\pi}/2$), broad peaks are observed near ( $\ensuremath{\pi},0$). Additional second and third neighbor hopping terms must be added to the $t\ensuremath{-}J$ Hamiltonian to account for both the dispersion and the line shape. It is found that this Hamiltonian can be used to explain the measured momentum dependent spectral function for hole-doped materials, both underdoped and overdoped, as well as electron-doped materials.