M. Karbach et al., STATIC STRUCTURE FACTORS OF THE XXZ-MODEL IN THE PRESENCE OF A UNIFORM-FIELD, Journal of physics. Condensed matter, 7(14), 1995, pp. 2829-2841
The static structure factors of the XXZ-model in the presence of a uni
form field are determined from an exact computation of the ground stat
es at given total spin on rings with N = 4, 6,..., 28 sites. Against t
he naive expectation, a weak uniform field strengthens the antiferroma
gnetic order in the transverse structure factor for the isotropic case
.