INVESTIGATION OF A HAMILTONIAN WITH 2 SOURCES OF ANISOTROPY - THE DZYALOSHINSKII-MORIYA AND SINGLE-SITE INTERACTIONS

La2CuO4 is an S = 1/2 system with almost tetragonal symmetry so that there is no single-site interaction term giving rise to anisotropy and the magnetic anisotropy of the system can be explained in terms of the Dzyaloshinskii-Moriya interaction which can lead to weak ferromagnetism even in a system with predominantly antiferromagnetic interactions. However, the closely related compounds, La2NiO4 and La2CoO4, are S = 1 and S = 3/2 systems, respectively, so that a single-site interaction term is present and it is of interest to see how this interaction changes the magnetic properties of these compounds. Here the classical magnetic ground states are calculated for model Hamiltonians, appropriate to the different low-temperature structural phases of the compounds, containing both interactions.