On some additional effects in Heisenberg ferromagnet caused by the presence of dipole-dipole interactions

The Heisenberg ferromagnet with dipole-dipole interactions was studied. It was shown that the presence of dipole-dipole interactions changes the direction of the quantization axis, gives the anharmonical correction to the low temperature magnetization proportional to the square of the temperature, increases the critical point and leads to a fusion process of elementary excitations. All the results obtained are valid only in the presence of an external magnetic field. The absence of the field requires a qualitatively new approach.