Dr. Marcello Civelli from University of Paris Sud, France, visited SCL from May 25 to 27, 2012, as a part of research activities of the "Quantum critical transport near the Mott metal-insulator transition" bilateral project. Marcello Civelli and his SCL host Darko Tanaskovic discussed ongoing and future research focusing on the physics of pseudogap phase in the cuprates and the quantum critical point in heavy fermion materials.

Dr. Civelli gave a talk on
"Superconducting gap versus pseudogap in high-Tc cuprates: a cellular dynamical mean field theory perspective"

Abstract:
Although discovered only three years after the discovery of high-temperature superconductivity, the physical origin of the pseudogap phase of cuprate superconductors (observed above the critical temperature Tc) and its relation with the superconducting phase is still shrouded in mystery. I will present a theoretical study of the pseudogap and superconducting phases in a minimal model (the two-dimensional Hubbard Model) of cuprate superconductors, carried out by means of the cellular dynamical mean field theory (CDMFT). Our results show that, while the superconducting gap is associated to Cooper pair formation, the pseudogap rises from the parent Mott insulator upon doping and it is intrinsically a normal-state property, which competes with superconductivity for the same electron-states in momentum space. In particular, recent 16-cluster-site CDMFT results show that the pseudogap has an s-wave symmetry, different from the well-known d-wave symmetry of superconducting gap, and that therefore pseudo and superconducting gaps have different origin. I will finally show that these results imply a peculiar behavior in the B2g Raman response, as observed in many materials of the cuprate family.