Ground state properties of two spin models with exactly known ground states on the square lattice
arXiv:cond-mat/0605464 · doi:10.1142/S0129183106009709
Abstract
We introduce a new two-dimensional model with diagonal four spin exchange and an exactly knownground-state. Using variational ansaetze and exact diagonalisation we calculate upper and lower bounds for the critical coupling of the model. Both for this model and for the Shastry-Sutherland model we study periodic systems up to system size 6x6.
to appear in IJMPC 17, 12 pages, 7 figures