ar X iv : c on d - m at / 9 50 10 01 v 1 3 J an 1 99 5 Self - Consistent Theory of Normal - to - Superconducting Transition

ar X iv : c on d - m at / 9 51 01 44 v 1 2 5 O ct 1 99 5 SPIN STIFFNESS IN THE HUBBARD MODEL

The spin stiffness ρ s of the repulsive Hubbard model that occurs in the hy-drodynamic theory of antiferromagnetic spin waves is shown to be the same as the thermodynamically defined stiffness involved in twisting the order parameter. New expressions for ρ s are derived, which enable easier interpretation , and connections with superconducting weight and gauge invariance are discussed.

ar X iv : c on d - m at / 9 50 80 44 v 1 1 1 A ug 1 99 5 Magnetism of superconducting UPt 3

ar X iv : c on d - m at / 9 50 81 42 v 1 3 1 A ug 1 99 5 Dual description of the superconducting phase transition

The dual approach to the Ginzburg-Landau theory of a Bardeen-Cooper-Schrieffer superconductor is reviewed. The dual theory describes a grand canonical ensemble of fluctuating closed magnetic vortices, of arbitrary length and shape, which interact with a massive vector field representing the local magnetic induction. When the critical temperature is approached from below, the magnetic vortices p...

ar X iv : c on d - m at / 9 50 80 62 v 1 3 1 Ju l 1 99 5 QUANTUM THEORY OF LARGE SYSTEMS OF NON - RELATIVISTIC MATTER

ar X iv : c on d - m at / 9 40 30 13 v 1 3 M ar 1 99 4 Nesting Mechanism for d - symmetry Superconductors ∗

A nested Fermi surface with nearly parallel orbit segments is found to yield a singlet d–wave superconducting state at high temperatures for a restricted range of the on–site Coulomb repulsion that avoids the competing spin density wave instability. The computed superconducting transition temperature drops dramatically as the nesting vector is decreased, in accord with recent photo–emission dat...