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Structure and Nanoscale Polarization Switching Induced by High Frequency Alternating Current in PbTiO3 Polycrystalline Films

PbTiO3 (PTO) films were successfully fabricated by sol-gel method. We studied the structure and the nanoscale polarization switching property using XRD and Piezoresponse Force Microscopy. The results reveal that the PTO films are single perovskite phase grain films with tetragonal structure, and are polycrystalline materials with no evidence of preferential orientation. The average grain size is about 150nm and a striped multi-domain structure is exhibited in individual grains. Under 15 kHz alternating current of PFM, a significant asymmetry of switching pattern was observed. We suggest that the cooperative action of the built-in electric field at the bottom interface and the PFM ac-voltage lead to the asymmetry switching.