Study of domain boundary polarization in (111)-cut [Pb(Mg_1/3Nb_2/3)O₃]_0.7(PbTiO₃)_0.3single crystal by piezoresponse force microscopy

Ferroelectric domain structure, especially the domain boundary polarization, in as-grown and poled (111)-cut PMN-30%PT single crystal has been studied by means of out-of-plane and in-plane piezoresponse force microscopies (PFMs). It revealed that the as-grown sample exhibits speckle-shaped microdomains, and the domain number distribution decreases exponentially as the domain size increases which can be described by the random field Ising model; in contrast, the poled sample shows stripe-shaped domains. Capacitive force-free PFM revealed a detailed domain boundary characteristic with net in-plane polarization. The presence of the in-plane polarization at the domain boundary also suggests the existence of orthorhombic phase in the rhombohedral matrix.