The multi-compensation temperatures for the four-sublattice Heisenberg ferrimagnetic system

The various types of magnetizations of a four-sublattice mixed-spin Heisenberg ferrimagnetic system are investigated with the help of the double-time temperature-dependent Green's function technique. One obtains the first-order phase transitions from ferrimagnetic states to ferrimagnetic or ferromagnetic states with respect to the choice of parameters in Hamiltonian. The system exhibits one-, two- and three-compensation temperatures where the sublattice magnetizations compensate each other at one- or more-points. We have managed to obtain three different spin configurations at the absolute temperature. Moreover, we observed a so-called frustrated spin.