Abstract
The mutual interactions between a structural transition and a ferroelectric transition are analyzed for different strain states in a pseudocubic (100) film by examining the equilibrium solutions of the total free energy as a function of polarization, strain and structural order parameter. The range of possible ferroelectric transition temperatures and the possible ferroelectric states of a strained film are determined with respect to the variation in the reported properties of bulk single crystals. The ferroelectric and structural domain morphologies at a biaxial tensile strain were predicted using phase-field simulations. It is shown that variations in the reported values of bulk properties and in the Landau energy coefficients from different literature sources lead not only to a wide range of possible transition temperatures at a given strain, but also to different ferroelectric states (e.g., polarization along the pseudocubic ⟨110⟩ vs ⟨100⟩ directions) thus different domain structures under a biaxial tensile strain. Both optical second harmonic generation and confocal scanning optical microscopy measurements demonstrate that the domain states in films strained at and 1.16% exhibit polar directions along the pseudocubic ⟨110⟩ directions within the pseudocubic (001) plane of the film.
3 More- Received 4 January 2006
DOI:https://doi.org/10.1103/PhysRevB.73.184112
©2006 American Physical Society