Ferroelastic domains in bilayered ferroelectric thin films Available to Purchase

We investigate theoretically ferroelastic domain fractions in a heteroepitaxial bilayer consisting of (001) tetragonal $PbZrxTi1−xO3$ and (001) rhombohedral $PbZr1−xTixO3$ on a thick (001) passive substrate as a function of the lattice misfit strain between layers and the substrate. By considering the self-strain in each layer and the indirect elastic interaction between the layers, we provide a numerical analysis of the relative domain fractions in the tetragonal layer of a $(001)PbZr0.2Ti0.8O3/(001)PbZr0.8Ti0.2O3$ and $(001)PbZr0.4Ti0.6O3/(001)PbZr0.6Ti0.4O3$ bilayer structure as a function of the tetragonal layer thickness on $(001)LaAlO3$⁠, $(001)SrTiO3$⁠, and (001) MgO. It is found that the elastic coupling between the tetragonal and rhombohedral layers leads to an excess elastic energy in the tetragonal layer, resulting in a two to three times increase in the ferroelastic domain volume fraction of the tetragonal layer compared to single-layer films of similar thickness. These results show alternate ways of engineering ferroelastic domain structures in ferroelectric thin films.