Münster 1999 – scientific programme

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TT: Tiefe Temperaturen

TT 15: Postersitzung II: Elektronische Eigenschaften (1-12), Josephson-Kontakte (13-27), Heavy Fermions (28-40), Theorie HTSL (41-48), M-I-Überg
änge, Korrelierte Systeme (49-79)

TT 15.46: Poster

Wednesday, March 24, 1999, 14:30–18:00, Foy

Self-consistent diagrammatic study of the SO(5) goldstone boson — •Jürgen Faaß, Enrico Arrigoni, and Werner Hanke — Institut für Theoretische Physik Universität Würzburg, D-97074 Würzburg

We study the q=(π,π) triplet particle-particle correlation function (“π”-operator) in the superconducting state of the extended Hubbard model by means of a self-consistent diagrammatic calculation (FLEX). The π operator has been identified as the goldstone boson which rotates between antiferromagnetism and superconductivity in the framework of the SO(5) theory of superconductivity [1,2] and as the responsible for the resonant neutron scattering peaks in the YBCO superconductors[3]. Our results show a quite broad peak, in contrast to results from the t-matrix approximation and from exact-diagonalization studies, but in agreement with Quantum-Monte-Carlo calculations. We discuss to what extent our results may be related to the use of a non-conserving approximation.

[1] S.-C. Zhang, Science 275, 1089 (1997)

[2] S. Meixner, W. Hanke, E. Demler, and S.-C. Zhang, Phys. Rev. Lett. 79, 4902 (1997)

[3] E. Demler and S.-C. Zhang, Phys. Rev. Lett 75, 4126 (95)