AC-Field Nonlinearity of KH2PO4

The temperature- and frequency dependent dielectric ac-field nonlinearity was investigated in the ferroelectric phase of KH2PO4 single crystals. Field induced deaging of pinned domain-walls dominates the nonlinearity at rather small field level, giving rise to the loss peak at the freezing temperature. The nonlinearity in moderate sub-switching fields obeys the generalized Rayleigh-law with frequency dependent exponent.