Re-Examination of the Dielectric Critical Slowing Down in Ferroelectric Triglycine Sulfate

Abstract

Dielectric dispersion of triglycine sulfate in the vicinity of the Curie temperature T_c was observed in the frequency range from 1 kHz to 1 GHz. The relaxation time τ of the dispersion is well expressed by the power law τ∝(T−T_c)^−Δ in the region 0.07 K\lesssimT−T_c\lesssim10 K with Δ=1.07 that is quite different from the non-classical value, Δ\simeq2⁄3, reported recently. The magnitude of the activation energy of dipole reversal is found to be about 3kT_c, which is fairly larger than that in the earlier study, indicating that the phase transition is of the order-disorder type.