Application of the Bogolyubov–Tyablikov method to investigation of spin-electron exchange interaction at arbitrary temperatures. The change in the properties of the magnetic subsystem

It is demonstrated that the improved Bogoliubov–Tyablikov method of approximate second quantization can be applied to the problem of a magnetic system interacting weakly with the electron subsystem of conductivity electrons or electrons of admixture centres in ferro- and paramagnetic semiconductors. The method makes it possible to find the changes of energy of elementary excitations in the magnetic subsystem at arbitrary temperatures.