Фрустрация обменно-стрикционного сегнетоэлектрического упорядочения и рост электрической поляризации областей фазового расслоения в твердых растворах R-=SUB=-0.8-=/SUB=-Ce-=SUB=-0.2-=/SUB=-Mn-=SUB=-2-=/SUB=-O-=SUB=-5-=/SUB=- (Er, Tb)

Abstract

The effect of rare-earth ions (R = Er^{3+}, Tb^{3+}, Ce^{3.75+}) on the dielectric properties and electric polarization induced by the local polar phase separation domains in solid solutions of multiferroics R_{0.8}Ce_{0.2}Mn_2O_5 (R = Er, Tb) is studied. A qualitative difference between these parameters and the previously studied in initial RMn_2O_5 crystals (R = Er, Tb) was found. It has been shown that the properties of the polar phase separation domains that arise in the subsystem of Mn^{3+} and Mn^{4+} ions due to the finite probability of tunneling of electrons between these ions substantially depend on the magnitudes of the crystal fields in which these domains are located. It was shown that the combined effect of E^{r3+}, Tb^{3+}, and Ce^{3.75+} ions significantly changes the crystal field in R_{0.8}Ce_{0.2}Mn_2O_5 (R = Er, Tb) compared to RMn_2O_5 (R = Er, Tb).