Analysis of the thermal hysteresis in partially deuterated tryglicine selenate

Abstract

Dielectric constant data on partially deuterated triglycine selenate (TGSe)_1-x, (DTGSe)_x for x = 0, 0.35, 0.80 show a steady increase of thermal hysteresis ΔT(x) with deuteration, in agreement with previous data by Gesi. In this work we correlate this observed thermal hysteresis with the parameter g(x) = (γ/β)N²μ² obtained from hysteresis loops data, in order to characterize the ferroelectric transition. For x = 0, the transition is close to a tricritical point (g ≌ 1/3) and we see that cooling very slowly through T_c under these quasitricritical conditions results in a very large residual contribution to the dielectric constant at the ferroelectric phase.