Temperature-dependent angle-resolved photoemission experiments were performed on overdoped single layer ${\mathrm{Bi}}_2{\mathrm{Sr}}_2{\mathrm{CuO}}_6$ ${(T}_c\sim 4\hspace{0.5em}\mathrm{K})$ and on the parent compounds ${\mathrm{Sr}}_2{\mathrm{CuO}}_2{\mathrm{Cl}}_2$ and ${\mathrm{Ca}}_2{\mathrm{CuO}}_2{\mathrm{Cl}}_2.$ Contrary to the more conventional results obtained on ${\mathrm{Bi}}_2{\mathrm{Sr}}_2{\mathrm{CuO}}_6,$ the parent compounds show strong temperature dependence over a wide energy range that is two orders of magnitude larger than the temperature scale involved. The doping dependence strongly suggests that the anomalous temperature dependence has its origin in the novel many-body physics in the Mott insulators. We consider the observed temperature dependence using a heuristic model with multiple initial and final states in the photoemission process. The nature of the multiple states and broad photoemission line shape in parent compounds is also given.

• Received 12 March 2001

DOI:https://doi.org/10.1103/PhysRevB.65.174516