Aging Dynamics in Ferroelectric Deuterated Potassium Dihydrogen Phosphate

TL;DR

This study investigates the aging behavior of ferroelectric DKDP, revealing large dielectric aging effects, memory of prior aging fields, and the role of hydrogen diffusion in domain wall disorder, with implications for ferroelectric stability.

Contribution

It provides new insights into the aging mechanisms in deuterated ferroelectric KDP, highlighting hydrogen diffusion and domain wall interactions as key factors.

Findings

Large dielectric aging in DKDP compared to KDP

Memory effects of prior aging fields in susceptibility

Aging effects persist after brief heating above Curie point

Abstract

Anomalously large dielectric aging is found in the high-susceptibility plateau ferroelectric regime of ~95% deuterated potassium dihydrogen phosphate (DKDP). Much less aging is found in non-deuterated KDP. Optical images of the DKDP domain structure show no dramatic change during aging. Small changes in electric field restore the pre-aged susceptibility, but the previous aging almost recovers after returning to the aging field. Susceptibility vs. field can show memory of at least two prior aging fields. Rectifying non-linear susceptibility develops for fields slightly above or below a prior aging field. Aging effects are not fully erased even by brief heating above the Curie point, indicating a role for diffusion of hydrogen to the domain walls, leaving changes in disorder that can survive temporary absence of domain walls. Abrupt random-sign steps in polarization on cooling are accompanied by increases in susceptibility, indicating competition between large-scale domain-wall interaction effects and effects of local interactions with disorder.