Fatigue as a local phase decomposition: A switching-induced charge-injection model

Following our recent experimental work on electrical fatigue [Phys. Rev. Lett. 97, 177601 (2006)], a theory of a charge-injection fatigue model is developed, emphasizing the extremely high depolarization electric field generated near the electrodes by bound charges at the tip of needlelike domains during switching. In particular, the relationship P-r(N)/P-r(0)similar to exp(-N/lambda), where N is the number of the fatigue cycles and lambda >> 1, is derived, which explains the statistical origin of the universality of the logarithmic fatigue behavior observed for various ferroelectric substances in the literature. The consistency of this model with extensive body of the experimental data has been discussed and a systematic picture of fatigue is established. In particular, the size effect/fatigue coupling, the fatigue-free behavior of low P-r samples, and the exaggerated fatigue data of Colla [Appl. Phys. Lett. 72, 2478 (1998)] at very low frequencies (mHz) are all well predicted by our model.