Pseudogap, van Hove singularity, maximum in entropy, and specific heat for hole-doped Mott insulators

The first indication of a pseudogap in cuprates came from a sudden decrease of the NMR Knight shift at a doping-dependent temperature T*(delta). Since then, experiments have found phase transitions at a lower T-phase*(delta). Using plaquette cellular dynamical mean field for the square-lattice Hubbard model at high temperature, where the results are reliable, we show that T*(delta) shares many features of T-phase*(delta). The remarkable agreement with several experiments, including quantum critical behavior of the electronic specific heat, supports the view that the pseudogap is controlled by a finite-doping extension of the Mott transition. We propose further experimental tests.