Abstract
We present exact models for an antiferromagnetic spin chain describing trimerization as well as for an antiferromagnetic spin chain describing tetramerization. These models can be seen as generalizations of the Majumdar-Ghosh model. For both models, we provide a local Hamiltonian and its exact threefold or fourfold degenerate ground state wave functions, respectively. We numerically confirm the validity of both models using exact diagonalization and discuss the low-lying excitations.
1 More- Received 16 April 2008
DOI:https://doi.org/10.1103/PhysRevB.78.134415
©2008 American Physical Society