Mean-field phase diagrams of $AT_2X_2$ compounds
  Magnetic-field -- temperature phase diagrams of the axial next-nearest-neighbor Ising model are calculated within the framework of a Landau-type expansion of the free energy derived from molecular-field theory. Good qualitative agreement is found with recently reported results on body-centered-tetragonal $UPd_2Si_2$. This work is expected to also be relevant for related compounds. 
M.L. Plumer (Centre de Recherche en Physique du Solide et   D\'epartement de Physique, Universit\'e de Sherbrooke, Sherbrook...