Frozen Superparaelectric State of Local Polar Regions in GdMn2O5 and Gd0.8Ce0.2MnO5

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

“…Note that the substantial difference in the behavior of the local conductivities and the electric polarization induced by local polar phase separation domains in GdMn 2 O 5 [9][10][11] and RMn 2 O 5 (R = Er, Tb) is due to the absence in GdMn 2 O 5 of additional barriers in the lattice, which are formed by Er 3+ and Tb 3+ ions with strong spin-orbit interactions. In the ground state of Gd 3+ ions, there is no spin-orbit interaction.…”

“…The choice of the high-frequency regime of the PUND method of measuring the hysteresis loops and also the temperature range of their existence suggest that the response on applied electric field pulses is due to the high-dynamic domains. They are local polar phase separation domains and the fluctuation region near the phase transition to the ferroelectric ordering [7][8][9].…”

“…At low temperatures (T < T C ≈ 30-40 K), the local phase separation domains in RMn 2 O 5 are isolated 1D superlattices of ferromagnetic layers containing Mn 3+ and Mn4+ ions in various proportions. In them, a set of ferromagnetic resonances [14][15][16] and the electric polarization [7][8][9] were observed in the directions of the magnetic and electric fields, respectively. At temperatures higher than 180 K, the interaction appears between local polar domains isolated before, and it forms 2D superstructures perpendicular to axis c. In these superstructures, the initial matrix layers alternated to the phase separation domains.…”

“…When studying the electric polarization induced by local polar domains in RMn 2 O 5 (R = Gd, Bi) [7][8][9], it was shown that, in these multiferroics, the local polar domains are the phase separation domains and they have the local ferroelectric ordering. The polarity of the phase separation domains in RMn 2 O 5 is due to the following two factors.…”

Electric Polarization in ErCrO3 Induced by Restricted Polar Domains

“…These conditions are as follows. The restricted-domain sizes R should be smaller than the correlation radius Rc of interaction between electric dipoles but larger than the critical radius Gd0.8Ce0.2Mn2O5 [13][14][15], as well as YCrO3 [11]. The electric polarization in YCrO3was observed both along the c axis and in the transverse (001) plane.…”