Optimal hole doping determined by Kondo effect and charge fluctuations

Abstract We investigate both the superconducting and normal states of the three-band t – J – U model applied to the hole-doped high- T c superconducting cuprate. We analyze the doping evolution of the superconducting transition temperature ( T c ) and local hole distribution for different values of J / t while determining the self-consistent d – p band hybridization. T c increases as J / t increases, since J / t represents a measure of the effective strength of the exchange and pair-hopping interactions leading to the superconductivity. The doping evolution of the local hole distribution reflects the Kondo effect, which enhances charge fluctuations at the O sites. In particular, the charge fluctuations are maximized approximately at the optimal hole doping. This suggests that the optimal hole doping is determined by the Kondo effect and charge fluctuations.