SO(5)-Symmetrie in elektronischen Leiterstrukturen : exakte Lösungen, Phasendiagramme und Korrelationen

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Spinon statistics in integrable spin-S Heisenberg chains

The spectrum of the integrable spin-S Heisenberg chains is completely characterized in terms of spin-1/2 spinons. In the continuum limit they form a quasi-particle basis to the higher level SU(2) Wess-Zumino-Witten (WZW) models. Enumerating the spinon states in finite systems we obtain effective single particle distribution functions for these objects which generalize Haldane's generalized exclusion principle to quasi-particles with non-Abelian exchange statistics.Comment: RevTeX, 5 pages, 1 eps-figure include

Electronic Ladders with SO(5) Symmetry: Phase Diagrams and Correlations at half-filling

We construct a family of electronic ladder models with SO(5) symmetry which have exact ground states in the form of finitely correlated wave functions. Extensions for these models preserving this symmetry are studied using these states in a variational approach. Within this approach, the zero temperature phase diagram of these electronic ladders at half filling is obtained, reproducing the known results in the weak coupling (band insulator) and strong coupling regime, first studied by Scalapino, Zhang and Hanke. Finally, the compact form of the variational wave functions allows to compute various correlation functions for these systems.Comment: RevTeX+epsf macros, 23 pp. including figure