We derive an evolutional equation incorporating the processes of spin-polarization transfer from an electron to a magnetic ion subsystem of a diluted magnetic semiconductor along with spin-lattice relaxation and spatial spin diffusion. Above equation has been obtained for nonequilibrium magnetization due to exchange scattering of photoexcited charge carriers by magnetic ions. We show that the mechanism of a band gap narrowing due to exchange scattering requires relatively low optical power to reach an optical bistability for pump frequency range close to crystal band gap. In a bulk crystal, only relatively small local area with essential magnetization enhancement can absorb optical power, thus forming a photoinduced magnetization wave. Spatial spin diffusion can be responsible for a motion of such
magnetization wave. We solve above derived equation both analytically for one-dimensional case and numerically otherwise and perform its stability analysis. We also evaluate numerically possible threshold of photoinduced magnetization wave excitation for typical diluted magnetic semiconductor A1-xIIMnxBVI and estimate its length and velocity of propagation.
The calculation of the correlation radius distribution function is performed for the cases of undamped and overdamped soft mode dispersion laws. Taking into account the correlation radius dependence on the random field and this field distribution function we carried out the theoretical calculation of the correlation radius distribution function dependence on temperature, damping coefficient and random field distribution function parameters. It was shown that at temperature higher than Burns temperature Td the most probable value of the correlation radius is equal to its maximal value independently on the system disorder, while in the dipole glass state it is close to the minimal value with broad tail of distribution function existing at broad temperature region.