Barkhausen noise probe of the ferroelectric transition in the relaxor PbMg1/3Nb2/3O3-12% PbTiO3

Barkhausen current noise is used to probe the slow field-driven conversion of the glassy relaxor ferroelectric state to an ordered ferroelectric state. The frequent presence of distinct micron-scale Barkhausen events well before the polarization current starts to speed up shows that the process is not a conventional nucleation-limited one. The prevalence of reverse switching events near the onset of the rapid part of the transition strongly indicates that electric dipole interactions play a key role. The combination of Barkhausen noise changes and changes in the complex dielectric response indicate that the process consists of an initial mixed-alignment domain formation stage followed by growth of the domains aligned with the applied field.