  The paper studies the spatial variation of the magnetization in a
nonconducting magnetic sample with an excess number of magnons in comparison to
the equilibrium. The phenomenon is considered using the Landau-Lifshits
equation with additional terms describing the longitudinal relaxation of the
magnetization, the magnon diffusion and the magnon creation by external
pumping. The free energy of the system is presented in the mean field
approximation. It is shown that, if the pumping exceeds some critical value,
regions of the new phase arise where the magnetic moments are oriented opposite
to the magnetization of the magnetic sample. The phenomenon is similar to the
appearance of droplets of the condensed phase in the supersaturated vapor. The
appearance of the new phase either in the form of a single domain or a
periodical lattice is demonstrated. The studied process is a competitor to the
process of the Bose-Einstein condensation of magnons.
