Competition between Superconductivity and SDW in the 2D Hubbard Model and Possibility of Superconductivity along a Stripe


The variational Monte Carlo calculation gives a finite bulk-limit value of superconducting (SC) condensation energy in the titles model with next-nearest-site transfer energy t' in an appropriate parameter region. The obtained SC condensation energy around the optimal doping is of the same order as the experimental value of about 0.26meV/site for YBCO. This assures the appropriateness of the 2D Hubbard model for cuprate high-Tc superconductors. However, the SDW condensation energy computed by the same method was found to overwhelm the former in the most parameter region where the superconductivity is expected to appear. The SC parameter region seems to be restricted to the highly hole-doped region. We look for the possibility of an inhomogeneous superconducting state coexisting with striped SDW in this low hole-doping SC region. In such a striped SDW state we have obtained an indication that superconductivity is brought about along the stripe in a mid-gap band presumably due to the two-band effect.

Article Outline

1. Introduction
2. Bulk-limit SC condensation energ
3. Competition with SDW
4. Stripe state and SC in low-hole-doping region
5. Summary