Strong- and weawk-coupling mechanisms for pseudogap in electron-doped cuprates

Using the two-particle self-consistent approach and cluster perturbation theory for the two-dimensional t-t'-t-U Hubbard model, we discuss weak- and strong-coupling mechanisms for the pseudogap observed in recent angle resolved photoemission spectroscopy on electron-doped cuprates. In the case of the strong-coupling mechanism, which is more relevant near half-filling, the pseudogap can be mainly driven by short-range correlations near the Mott insulator. In the vicinity of optimal doping, where weak-coupling physics is more relevant, large antiferromagnetic correlation lengths, seen in neutron measurements, are the origin of the pseudogap. The t-J model is not applicable in the latter case. (c) 2006 Elsevier Ltd. All rights reserved.