Domain structure in ferroelectric-ferromagnetic films

The conditions for the phase transition to the ferroelectromagnetic phase in ferroelectric-ferromagnetic films through the mechanism of the loss of stability of the initial homogeneous state have been considered. The geometry of the domain structure and the temperature of the transition to the inhomogeneous state have been determined. The condition for the phase transition to the ferroelectromagnetic phase has been established and determined by the relationship between the temperature-dependent coefficients of the expansion of the thermodynamic potential into a series in terms of the polarization and magnetization vector components. The influence of free charge carriers on the geometry of the domain structure and the transition temperature has been studied. The possible existence of a single-domain state has been discussed. The permittivity of a multidomain sample has been determined. The feasibility of exploiting the studied material for nondestructive recording and reading of information has been noted.