Gossamer superconductivity, new paradigm?

We review our recent works on d-wave density wave (dDW) and gossamer superconductivity (i.e. d-wave superconductivity in the presence of dDW) in high-Tc cuprates and CeCoIn5. a) We show that both the giant Nernst effect and the angle dependent magnetoresistance (ADMR) in the pseudogap phases of the cuprates and CeCoIn5 are manifestations of dDW. b) The phase diagram of high-Tc cuprates is understood in terms of mean field theory, which includes two order parameters Δ1 and Δ2, where one order paremeter is from dDW and the other from d-wave superconductivity. c) In the optimally to the overdoped region we find the spatially periodic dDW, an analogue of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, becomes more stable. d) In the underdoped region where Δ2/Δ1<<1 the Uemera relation is obtained within the present model. We speculate that the gossamer superconductivity is at the heart of high-Tc cuprate superconductors, the heavy-fermion superconductor CeCoIn5 and the organic superconductors κ-(ET)2Cu(NCS)2 and (TMTSF)2PF6. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)