Dielectric response of the relaxor ferroelectric Pb(Mg1/3Nb2/3)O3 in the nonergodic state after a DC electric field is turned off

The Pb(Mg_1/3Nb_2/3)O₃ (PMN) relaxor system is used as an example to analyze the temperature dependences of the low-frequency dielectric permitivity (?′(T)) measured during zero-field heating (ZFH) from T = 10 K to T = 300 K after using different field cooling (FC) conditions. No changes in the temperature dependences of the permittivity have been detected during the transition from a nonergodic relaxor state (NERS) into an ergodic relaxor state (ERS) (at T _f ≈ 216 K). However, the difference Δ?′(T) between the curves corresponding to different field cooling conditions in the same electric field has different shapes and different values below and above T → (T _f + 9 K)^? (for E _dc = 1.52 kV/cm). The reduced permittivities ?′_r(T, f) recorded under different cooling conditions are shown to change their behavior when passing through T = T _f + 9 K. In NERS, these curves diverge: the stronger the field (0 ≤ E _dc ≤ 3 kV/cm), the larger the divergence. In ERS, however, the ?′_r(T, f) curves coincide under different cooling conditions irrespective of the field. The character of the changes in Δ?′(T) and ?′_r (T, f) during the NERS-ERS transition is frequency-independent. The difference in the behavior of the dielectric response during ZFH after cooling in different (ZFC, FC) modes (even in a weak field), for both transition through T _f and cooling down to T = 10 K, indicates different NERSs forming under these conditions. The contribution to ?′(T) from slowly relaxing regions (ω ～ 0.1 mHz), whose polarization is reoriented after the field is turned off, is responsible for the fact that, during the NERS-ERS transition, the ?′_r(T, f) curves coincide at a temperature that is higher than T = T _f.