Appearance of narrow band with hole doping in high Tc superconducting oxides

The effect of hole doping on the electronic states in high T_c superconducting oxides is examined. Assuming the periodic Anderson model for the CuO system composed of highly correlated copper d electrons and oxigen p electrons, we calculated the density of states in the low energy region in the case that the bare p band is situated inside the Hubbard gap. We found that a narrow band like a heavy fermion band appears near the Fermi level inside the charge transfer gap when the hole number is small. This result explaines a new optical absorption band observed in La_2-xSr_xCuO₄.