Local electromechanical properties of PbMg_1/3Nb _2/3O₃ thin films studied by piezoelectric force microscopy

The local electromechanical response of epitaxial thin films of relaxor ferroelectric PbMg1/3Nb2/3O3 (PMN) was studied at room temperature using Piezoresponse Force Microscopy (PFM). In the virgin films, no piezoelectric contrast was detected. An onset of the polar state was induced locally by applying an external bias to the tip. After removing the voltage, a relaxation of the locally induced polarization was observed. The relatively small threshold electric field and short critical time for onset of the polar state, and the relatively long relaxation time are discussed in terms of peculiarities of both PFM technique and thin films.