A quantum phase transition and novel spin phases in the three-band Hubbard model*

The three-band Hubbard model captures several key features of the Copper-Oxide planes in cuprate superconductors, and provides the simplest model beyond the minimal one-band Hubbard model. Combining extended mean-field calculations with cutting-edge correlated methodologies we are performing an extensive study of the model in the relevant regions of the parameter space. We address the nature of the spin and charge order, as well as of pairing correlations, as a function of the interaction strength and the charge transfer energy in the ground state of this model. We find evidence of a quantum phase transition at half-filling and very interesting novel spin states in the underdoped regime.