Canted-to-canted singular points in ferrimagnetic polycrystalline magnetization curves

The study of singularities in the magnetization curve of magnetic materials is since a long time a well known tool to gain insight into the material properties. Such singularities are usually due to discontinuous magnetization processes related to magnetic anisotropy, therefore an ideal investigation scheme would comprise magnetization measurements along the symmetry axis of a single crystal. As a matter of fact, one has to often deal with polycrystalline samples: in that case, however, the singularities can still be detected at the same positions as for the single crystal case. In this paper we focus on ferrimagnetic materials with uniaxial magnetic anisotropy. After recalling how theory allows us to calculate the critical fields at which singularities occur when the magnetic field is applied along a symmetry direction, we show that a new type of singular point not yet reported in the literature can exist. Such new singularity appears only in polycrystalline samples. We derive its analytical expression and we also show that, in spite of the need to overcome the exchange interaction, combinations of the material parameters can occur for which it falls inside experimentally accessible region.