  We present an angle-resolved photoemission spectroscopy (ARPES) study of a
Mott-Hubbard-type bismuth cobaltate system across a metal-insulator transition.
By varying the amount of Pb substitution, and by doping with Sr or Ba cation, a
range of insulating to metallic properties is obtained. We observe a systematic
change in the spectral weight of the coherent and incoherent parts, accompanied
by an energy shift of the incoherent part. The band dispersion also shows the
emergence of a weakly dispersing state at the Fermi energy with increasing
conductivity. These changes correspond with the changes in the
temperature-dependent resistivity behavior. We address the nature of the
coherent-incoherent parts in relation to the peak-dip-hump feature seen in
cuprates superconductors.
