Similarity of mechanisms of formation of phase separation domains in $_3$Fe$_5$O$_{12}$, EuFeO$_3$, YCrO$_3$, Eu$_2$CuO$_4$, and RMn$_2$O$_5$ multiferroics (brief review)

The study of the magnetic dynamics of some magnetic crystals with $3d$ ions having different symmetries reveals phase separation domains. They turn out to be similar to phase separation domains in RMn$_2$O$_5$ multiferroics with charge ordering. This apparently occurs because flexoelastic magnetoelectric inhomogeneities with an increased electron density appear in domain walls of the studied crystals; this electron density changes the charge composition of ions in such walls. In this case, change in the valences of $3d$ ions at which their charge ordering occurs becomes energetically favorable. As a result, phase separation similar to that formed in RMn$_2$O$_5$ multiferroics appears in the domain walls of these crystals.