Coexistence of two universal relaxations in the glassy freezing of a deuteron dipole glass

Abstract

A deuteron dipole glass Rb1−x(ND4)xD2PO4 (DRADP-x, x = 0.47) was studied on glassy freezing by low-frequency dielectric measurements at low temperatures of slow dynamic freezing. A very broad distribution of relaxation times (relaxation frequencies) was observed to show an apparent crossover behavior from the relaxation time distributions with a long-time (low-frequency) tail to the distributions with a short-time (high-frequency) tail as temperature was lowered to below 40 K. We show that this apparent crossover behavior may be originated by two competing relaxations in coexistence: one characterized by an Arrhenius law and the other by an inverse Arrhenius law temperature dependence, corresponding to the two slow-relaxation modes (C < 0 and C > 0) of the dynamically correlated domains (DCDs) model of Chamberlin et al.