Static Structure Factors of the XXZ-Model in the presence of a uniform   field
  The static structure factors of the XXZ model in the presence of uniform field are determined from an exact computation of the groundstates at given total spin on rings with $N=4,6,\ldots,28$ sites. In contrast to the naive expectation a weak uniform field strengthens the antiferromagnetic order in the transverse structure factor for the isotropic case. 
M. Karbach, K.-H. M\"utter, M. Schmidt