Quasi-static electric field–temperature diagrams in epitaxial relaxor ferroelectric films

Quasi-static polarization induced by dc electric field was studied in a broad range of temperatures in epitaxial films of relaxor ferroelectric PbMg1/3Nb2/3O3 and PbSc1/2Nb1/2O3. The electric field was applied and the response was measured along the out-of-plane crystal direction of the epitaxial perovskite-structure (001) oriented films. The films remained in the relaxor state in zero-field cooling. A new polar state can be induced by electric field at a critical temperature below 100 K. The critical field and the induced polarization increased on cooling and reached the bulk-like values at 20 K. The orientational anisotropy of thin-film dipolar systems is discussed as a possible reason for the observed stable relaxor state.