Unconventional spin density waves in quasi-one dimensional systems

We consider the possibility of formation of an unconventional spin density wave (SDW) in quasi-one dimensional electronic systems. In analogy with unc onventional superconductivity, we develop a mean held theory of SDW allowin g for the momentum dependent gap Delta(k) on the Fermi surface. The excitat ion spectrum and basic thermodynamic properties of the model are found to b e very similar to those of d-wave superconductors in spite of the different topology of their Fermi surfaces. Among the transport properties the frequ ency dependent conductivity in directions perpendicular to the linear chain direction is evaluated for various gap functions, and found to reflect the maximum gap value.