Scaling behavior of ferroelectric hysteresis loop in pulsed-laser-deposited SrBi2Ta2O9 thin film

Abstract

Ferroelectric SrBi2Ta2O9 thin films were grown on a highly oriented Pt/Ti/SiO2/Si substrates using pulsed laser ablation. The hysteresis loop of ferroelectric SrBi2Ta2O9 was studied as a function of applied field amplitude. A scaling analysis of ferroelectric hysteresis loop area showed A∝Eα. The value of scaling exponent, α=0.40, is not similar to the reported theoretical and experimental values. This result shows the possibility that both ferroelectric bulk and thin-film systems may have different universal behaviors. Influence of potential in the surface of SrBi2Ta2O9 thin film was measured in the dc applied field range from 0 to 8 V by using electro force microscopy. Roughness of surface potential of SrBi2Ta2O9 thin film changed rapidly around the coercive voltage, Vc∼1.5 V. It is believed that the switching effect of SrBi2Ta2O9 thin film includes surface polarization at the surface of the thin film as well as pure spontaneous polarization in the bulk.