Tuning the remanent polarization of epitaxial ferroelectric thin films with strain

The effect of biaxial strain on the remanent polarization of epitaxial thin films of various ferroelectric materials is studied using phenomenological Landau–Devonshire theory. It is shown that the strain dependences of the remanent polarizations are strongly dependent on crystal symmetries and film orientations. For (001)p-oriented ferroelectric films with (distorted) rhombohedral symmetry, strain-induced polarization rotation leads to stronger strain dependences than in ferroelectric films with tetragonal or orthorhombic symmetries. For (111)p-oriented ferroelectric films with rhombohedral symmetry, however, the remanent polarization is less sensitive to the biaxial strain.