4 research outputs found
Optimum ground states for spin- chains
We present a set of {\em optimum ground states} for a large class of
spin- chains. Such global ground states are simultaneously ground
states of the local Hamiltonian, i.e. the nearest neighbour interaction in the
present case. They are constructed in the form of a matrix product. We find
three types of phases, namely a {\em weak antiferromagnet}, a {\em weak
ferromagnet}, and a {\em dimerized antiferromagnet}. The main physical
properties of these phases are calculated exactly by using a transfer matrix
technique, in particular magnetization and two spin correlations. Depending on
the model parameters, they show a surprisingly rich structure.Comment: LaTeX, 22 pages, 6 embedded Postscript figure