Superconductivity and antiferromagnetism in the three-dimensional Hubbard model

Abstract

The interplay between antiferromagnetism and superconductivity is studied by using the three-dimensional nearly half-filled Hubbard model with anisotropic transfer matrices tz and t⊥. The phase diagrams are calculated for varying values of the ratio rz=tz/t⊥ using the spin fluctuation theory within the fluctuation-exchange approximation. The antiferromagnetic phase around the half-filled electron density expands while the neighboring phase of the anisotropic dx2−y2-wave superconductivity shrinks with increasing rz. For small rz Tc decreases slowly with increasing rz. For moderate values of rz we find a second order transition, with lowering temperature, from the dx2−y2-wave superconducting phase to a phase where an incommensurate spin density wave (SDW) coexists with dx2−y2-wave superconductivity. Resonance peaks discussed previously for two-dimensional (2D) superconductors are shown to survive in the dx2−y2-wave superconducting phase of 3D systems. Soft components of the incommensurate SDW spin fluctuation mode grow as the coexistent phase is approached.

Source-reported materials — not catalogue approval

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