Phase diagram of low-dimensional antiferromagnets with competing order   parameters: A Ginzburg-Landau-theory approach
  We present a detailed analysis of the phase diagram of antiferromagnets with competing exchange-driven and field-induced order parameters. By using the quasi-1D antiferromagnet BaCu_2Si_2O_7 as a test case, we demonstrate that a model based on a Ginzburg-Landau type of approach provides an adequate description of both the magnetization process and of the phase diagram. The developed model not only accounts correctly for the observed spin-reorientation transitions, but it predicts also their unusual angular dependence. 
V. N. Glazkov, F. Casola, H.-R. Ott, T. Shiroka
cond-mat.str-el