Pseudo and superconducting gaps in cuprates: not so much friends at the end ?
Lab. de Phys. des Solides, Orsay
Lundi 26/11/2012, 14:00
Salle Claude Itzykson, Bât. 774, Orme des Merisiers
According to the famous Bardeen-Cooper-Schrieffer (BCS) theory, superconductivity appearing under a critical temperature Tc is the outcome of the electron pairing, unambiguously signaled by the appearance of a superconducting gap in the electronic spectrum. In stark contrast with BCS, high-Tc cuprate superconductors display a gap (the pseudogap) even above the superconducting Tc. The relationship between the superconducting gap and the pseudogap has been a controversial open issue, hitting at the heart of the high-Tc superconducting mechanism. Our theoretical result, based on a cluster extension of the dynamical mean field theory, shows that the pseudogap and the superconducting gap have a clear different structure, hence different origins. Signatures in line with our finding have been observed in angle-resolved photo-emission spectroscopy, scanning tunneling spectroscopy and above all in Raman spectroscopy, where peculiar properties are well explained within our theory. These results would put definitive constrains on the theories of high-Tc superconductivity.