Ground state and zero temperature phase diagrams of the XXZ antiferromagnetic spin-$\text{1}\text{2}$ chain

Abstract

An expression of the XXZ model is given from which the Ising, isotropic XY and Heisenberg models may be more properly obtained by varying only one anisotropy parameter. The ground state and spin configuration of the antiferromagnetic quasi-classical $\text{s =}\text{1}\text{2}$XXZ chain in a magnetic field of arbitrary direction are studied. The phase diagrams with a longitudinal (h_⊥ = 0) and a transverse field (h_‖ = 0) are presented. Because we take into account an effect of anisotropy in the Zeeman interaction, the phase diagrams are quite different from those given by Kurmann, et al. [Physica A 112 (1982) 235]. A ferromagnetic-antiferromagnetic first order phase transition is indicated for the Ising case with h_⊥=0.