We use the matrix product approach to construct all optimum ground states of general anisotropic spin-2 chains with nearest-neighbour interactions and common symmetries. These states are exact ground states of the model and their properties depend on up to three parameters. We find three different antiferromagnetic Haldane phases, one weak antiferromagnetic and one weak ferromagnetic phase. The antiferromagnetic phases can be described as spin liquids with exponentially decaying correlation functions. The variety of phases found with the matrix product ansatz also gives insight into the behaviour of spin chains with arbitrary higher spins.
EPL (Europhysics Letters)
- Pub Date:
- September 2002
- Quantized spin models;
- Condensed Matter - Strongly Correlated Electrons
- 7 pages, 2 figures, to be published in europhysics letters, uses epl.cls