Electric-field-induced transformations are studied experimentally in cube-on-cube-type epitaxial film of relaxor ferroelectric (FE) ${\text{PbMg}}_{{}^1/{}_3}$${\text{Nb}}_{{}^2/{}_3}$${\text{O}}_3$ grown on (001) MgO substrate. The dielectric response, polarization, and current are measured along the out-of-plane $\langle 100\rangle$ direction of the film and analyzed as a function of temperature, frequency, and applied field. Compared to the $\langle 100\rangle$ crystal, transformation of the low-temperature relaxor state to a new state in the (001) film takes place at considerably lower temperatures and larger fields. Based on the found bisigmoidal shape and the two scaling regimes of the current-voltage curves, the two corresponding electric-field-induced processes are suggested to be dipolar flips and flow of a phase boundary in the film. The field-induced state in the film is dynamic and unstable, and it differs from the field-induced FE state in the crystal. The robustness of the relaxor state to electric field in the film is discussed in relation to spatial anisotropy of the dipolar system in the (001) film.

• Received 9 January 2014

DOI:https://doi.org/10.1103/PhysRevB.89.094106