The dc-bias field-dependence of the complex dielectric permittivity in potassium dihydrogen phosphate (KDP) crystal has been studied across its ferroelectric transition temperature, revealing novel effects of the applied field on the domain wall dynamics. Exactly at the domain-wall freezing temperature T_(f), the dielectric constant (epsilon') is dramatically field-insensitive while the dielectric loss (epsilon") is maximally frequency-dispersive. The relaxational behaviour of domain-wall motion manifests double Arrhenius feature - evident for two types of domain-wall kinetic evolution; their activation energies having opposite dependences on the applied field. Rao and co-workers have reported using PFM to study the D-W dynamics [1]. Our results on the bulk dielectric property using appropriate probe illustrate higher sensitivity, making the precision measurements of rather small effects, yet unreported in the KDP literature.
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