The ac sub-coercive-field dielectric resonses of (Pb, Sr)TiO₃ films at low temperature

The evolutions of the ac sub-coercive-field dependent dielectric responses and ferroelectric properties with the temperature in (Pb,Sr)TiO₃ (PST) films were investigated in this study. It was found that the remanent polarization (Pr) and coercive field (Vc) monotonically increase with the decreasing temperature, indicating that the ferroelectric domain wall (DW) motion is a thermal-driven processes. Then, ac sub-coercive-field dependent dielectric responses were analyzed in the frame of the hyperbolic law. The contributions of intrinsic lattice, reversible process of DW motion, and irreversible DW motion to sub-coercive-field dielectric responses were extracted. It is shown that the contribution of intrinsic lattice monotonically increases at higher temperatures due to ferroelectric phase nature of PST films at low temperature. The thermal-activated depinning domain wall with charged defects make reversible and irreversible DW motions sharply motivated with increasing temperature except a platform behavior of irreversible DW motion in the temperature range from 170 to 220 K. The competition between the domain configuration evolution and the thermally-activated depinning process may result in this platform behavior of domain wall motion.