Strain Effects of the Structural Characteristics of Ferroelectric Transition in Single-Domain Epitaxial BiFeO₃ Films

Structural characteristics of phase transition in single-domain epitaxial BiFeO₃ films are studied by the Landau–Devonshire theory. It is predicted that remanent polarization shows strong strain dependence for different temperatures while spontaneous polarization is almost independent of strain over a wide temperature (0–500 °C). We also obtain the thickness dependence of the c−axis lattice parameter and Curie temperature, and make a comparison between the polarization rotation angle and the angle attributed to the structural evolution in epitaxial (001)_p BiFeO₃ films grown on SrTiO₃ substrates. The theoretical results are in agreement with recent experimental and theoretical data. Our calculations show that the clamping effect should also be taken into account in order to depict the mechanism of the polarization rotation completely.