Controlling the properties of a Ba$_x$Sr$_{1-x}$TiO$_3$ ferrelectric film

A method is proposed to control the properties of thin ferroelectric films under forced deformation due to the size mismatch of the crystalline lattices of film and substrate materials and due to the difference of their thermal expansion coefficients. Control is based on additional mechanical deformation of the substrate. A model of a single-crystal Ba$_x$Sr$_{1-x}$TiO$_3$ film is studied within the framework of phenomenological theory using the Landau potential. It is shown that additional uniaxial deformation of the substrate in a Ba$_x$Sr$_{1-x}$TiO$_3$ film changes the material constants of the film. Abnormal change occurs at deformation values close to the values at which the phase state of the film changes. The generation of surface acoustic waves is studied. The results of modeling simulations indicate the possibility of controlling the excitation of surface acoustic waves in the film–silicon substrate heterostructure.