Pseudogap formation due to charge-transfer transition and Kondo effect

We investigate the doping evolution of the electronic state of the three-band t -J -U model considering the normal state of the hole-doped high-Tc superconducting cuprate. In our model, when some number of holes are doped into the undoped state, the d electron exhibits the charge-transfer (CT)-type Mott-Hubbard transition along with a chemical potential jump. A reduced CT gap is formed from the p band and the coherent component of the d band, and it shrinks due to charge fluctuations as more holes are doped as in the pseudogap (PG) phenomenon. This trend is reinforced as the d -p band hybridization is increased, and a Fermi liquid state is retrieved as in the Kondo effect. These suggest that the PG in the hole-doped cuprate emerges due to the CT transition and the Kondo effect.