Abstract
Finite-cell calculations (up to spins) have been performed on the spin-1 Heisenberg-Ising chain with an uniaxial anisotropy, . From a scaling analysis of the gap between the ground state and the first excited state, a phase diagram has been drawn in the () plane and the transition lines between the "ferromagnetic," ," "singlet-ground-state," and "antiferromagnetic" phases have been estimated for the infinite- system. One of the most important results is that a singlet-ground-state phase with a nonzero gap exists in an extended range of and values including the Heisenberg point , , in contrast with the spin- case. Moreover, for , the gap decreases with increasing positive anisotropy , goes through a minimum, estimated to be zero, and then increases with .
- Received 28 March 1983
DOI:https://doi.org/10.1103/PhysRevB.28.3914
©1983 American Physical Society