AC-Field Nonlinearity of KH₂PO₄

Aging dynamics in ferroelectric deuterated potassium dihydrogen phosphate

“…Measurement of dielectric response for KDP is complicated by large non-linear effects, attributed to weakly pinned domain walls 7 , found at relatively low fields. Fig.…”

“…1 illustrates the voltage-dependence of the response for DKDP, showing effects very similar to those reported for KDP. 7 Most of our measurements were made using 1V rms or, for the secondorder non-linear response, 2V rms-large enough to be well into the non-linear regime in which several frequency-dependent features show up that are not apparent in the linear regime, and for which aging effects are particularly evident. 7 Broad-band dielectric response data were taken 11/16/16 6 using QuadTech 7600 Plus LCR meter using 1 V rms ac bias, and thus also well into the nonlinear regime.…”

“…7 Most of our measurements were made using 1V rms or, for the secondorder non-linear response, 2V rms-large enough to be well into the non-linear regime in which several frequency-dependent features show up that are not apparent in the linear regime, and for which aging effects are particularly evident. 7 Broad-band dielectric response data were taken 11/16/16 6 using QuadTech 7600 Plus LCR meter using 1 V rms ac bias, and thus also well into the nonlinear regime. Although the response measured is therefore not, strictly speaking, the linear dielectric coefficient, we will still refer to the apparent coefficient determined from the current/voltage ratio as ε' for brevity.…”

“…7 We then present results showing that the aging effect in DKDP is not due to domain growth, and that the settling of interacting domain walls into the frozen set found below the plateau competes with rather than enhances the aging, leaving domain-wall pinning effects as the mechanism. …”

“…In KDP and DKDP, the FE phases show unusual plateaus in the real dielectric constant ε' over a temperature range below the Curie temperature, T C , with the large susceptibility arising from a dense array of 180° domain walls. [2][3][4] The origins of the abrupt loss of susceptibility at low temperature are not fully understood, but they may be driven by a phase transition or sharp crossover, involving interactions among the domain walls 3,5 and probably pinning by interaction with disorder 6,7 . This effect motivates studying dynamical symptoms of such cooperative behavior in the plateau region, such as the aging effects-i.e.…”