Various ordered states in a 2D interacting electron system close to an electronic topological transition

We consider a 2D electron system on a square lattice with hopping beyond ne arest neighbors. The existence of the quantum critical point associated wit h an electronic topological transition in the noninteracting system results in density wave (DW) and high-temperature d-wave superconducting (dSC) ins tabilities in the presence of an exchange interaction J. We analyse differe nt DW ordering such as isotropic Spin DW (SDW), d-wave SDW, isotropic Charg e DW (CDW) and d-wave CDW. The coexistence of dSC and SDW orders leads nece ssarily to the existence of a third order which is a pi triplet superconduc ting (PTS) order. A new phase diagram with a mixed phase of SDW, dSC and PT S order is found. The theory is applied to high-T-c cuprates. (C) 2000 Else vier Science B.V. All rights reserved.