Avalanche dynamics of ferroelectric phase transitions in BaTiO_3 and 0.7Pb(Mg_(2/3)Nb_(1/3))O_3- 0.3PbTiO_3 single crystals

摘要

The motion of phase fronts during a ferroelectric phase transition is intermittent and follows avalanche dynamics. In the present study, we show that an intermittent propagation mode generates spikes of depolarization currents at an extremely slow heating rate of 0.05 K/min in BaTiO3(BTO) and 0.7Pb(Mg2/3Nb1/3)O-3-0.3PbTiO(3) (PMN-PT) single crystals. Such "jerks" are indicative of avalanche dynamics, and their energy exhibits a power law distribution with exponents of epsilon = 1.3 +/- 0.10 and epsilon = 1.5 +/- 0.10 for BTO and PMN-PT, respectively. The rate of aftershocks after big events decays as an Omori-like power-law and interevent times are characterized by a universal double power-law distribution, indicating the critical temporal correlations between the avalanche events.