The kinematic interaction of spin-waves is found to lead to additional energy levels even in the presence of an interaction of spin-waves with mechanical vibrations of the crystal molecules. Those levels appear in the region of large wave-vectors k 107cm−1. The lower limit of this interval is...

An equivalent Hamiltonian method for the analysis of isotropic antiferromagnets is proposed. The Hamiltonian does not contain the terms corresponding to the processes of non-conservation of spin waves and gives the possibility to perform the calculations with a limited and controlled error. The...

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...