Effect of Rare-Earth Ions on an Electric Polarization Induced by the Phase Separation Domains in RMn2O5 (R = Er, Tb)

The effect of rare-earth ions (R = Er3+, Tb3+) with strong spin-orbit coupling on the dielectric properties and the electric polarization induced by local polar phase separation domains in RMn2O5 multiferroics has been studied. These parameters is found to be qualitatively distinguished from those studied before in GdMn2O5, in which Gd3+ ion in the ground 8S7/2 state is weakly bounded with the lattice. It is shown that the properties of the polar phase separation domains, which form in the subsystem of Mn3+ and Mn4+ ions, are substantially dependent on the values of crystal fields, in which these domains exist.