Magnetic dynamics of phase separation domains in GdMn$_{2}$O$_{5}$ and Gd$_{0.8}$Ce$_{0.2}$Mn$_{2}$O$_{5}$ multiferroics

Specific features of the magnetic properties and magnetic dynamics of isolated phase separation domains in GdMn$_{2}$O$_{5}$ and Gd$_{0.8}$Ce$_{0.2}$Mn$_{2}$O$_{5}$ have been investigated. These domains represent 1D superlattices consisting of dielectric and conducting layers with the ferromagnetic orientation of their spins. A set of ferromagnetic resonances of separate superlattice layers has been studied. The properties of the 1D superlattices in GdMn$_{2}$O$_{5}$ and Gd$_{0.8}$Ce$_{0.2}$Mn$_{2}$O$_{5}$ are compared with the properties of the previously investigated $R$Mn$_{2}$O$_{5}$ ($R$ = Eu, Tb, Er, and Bi) series. The similarity of the properties for all the $R$Mn$_{2}$O$_{5}$ compounds with different $R$ ion types is established. Based on the concepts of the magnetic dynamics of ferromagnetic multilayers and properties of semiconductor superlattices, a 1D model of the superlattices in $R$Mn$_{2}$O$_{5}$ is built.