Local twin domains and tip-voltage-induced domain switching of monoclinicMCphase inPb(Mg1/3Nb2/3)O3−0.34PbTiO3single crystal revealed by piezoresponse force microscopy

The monoclinic (M) phases in high-performance relaxor-based ferroelectric single crystals have been recognized to be a vital structural factor for the outstanding piezoelectric property. However, due to the complexity of the structure in M phases, the understanding about it is still limited. In this paper, the local twin domains and tip-voltage-induced domain switching of the ${\mathrm{M}}_C$ phase in $\mathrm{Pb}(\mathrm{M}{\mathrm{g}}_1/3\mathrm{N}{\mathrm{b}}_2/3){\mathrm{O}}₃\ensuremath{-}0.34\mathrm{PbTi}{\mathrm{O}}₃$ (PMN-0.34PT) single crystal have been intensively investigated by piezoresponse force microscopy (PFM). By theoretically analyzing the experimental patterns of domain walls on the ${(001)}_C$ face, the specific ${\mathrm{M}}_C$ twin domains in the initial annealed state of a selected area have been clarified, and the polarization orientation of the ${\mathrm{M}}_C$ phase in this sample is determined to be at an angle of ${29}^{\ensuremath{\circ}}$ to the ${\ensuremath{\langle}001\ensuremath{\rangle}}_C$ directions. In addition, based on the evolution of domains and the motion of domain walls under the step-increased PFM tip dc voltage (${V}_{\mathrm{dc}}$), the switching process and features of different types of ${\mathrm{M}}_C$ domain variants are visually revealed.