Polarization rotation of field-induced phase transformations was observed by means of a polarizing microscope on a (001)-cut single crystal $\mathrm{Pb}({\mathrm{Mg}}_{1/3}{\mathrm{Nb}}_{2/3}{)}_{0.76}{\mathrm{Ti}}_{0.24}{\mathrm{O}}_3$ (PMNT24%) at room temperature with an electric field applied along the [001] direction. A hysteresis loop was also measured for comparison. As the electric field increases, polarizations of rhombohedral $R$ domains rotate toward the [001] tetragonal $T_{001}$ phase through $M_A$-type monoclinic distortions, i.e., $\overrightarrow{R}{M}_A\to T_{001}.$ The crystal cannot entirely reach the $T_{001}$ phase as the field approaches 44 kV/cm. In addition, spotlike domains that perhaps correspond to $M_B$-type monoclinic or triclinic phases were also observed. This field-induced phase transformation is strongly irreversible.

• Received 3 June 2003

DOI:https://doi.org/10.1103/PhysRevB.69.172101