Fine tuning epitaxial strain in ferroelectrics: Pb_xSr_(1-x)TiO_3 on DyScO_3

摘要

Epitaxial strain can be efficiently used to modify the properties of ferroelectric thin films. From the experimental viewpoint, the challenge is to fine-tune the magnitude of the strain. We illustrate here how, by using a suitable combination of composition and substrate, the magnitude of the epitaxial strain can be controlled in a continuous manner. The phase diagram of Pb_xSr_(1-x)TiO_3 films grown epitaxially on (110)-DyScO_3 is calculated using a Devonshire-Landau approach. A boundary between in-plane and out-of-plane oriented ferroelectric phases is predicted to take place at x ≈ 0.8. A series of Pb_xSr_(1-x)TiO_3 epitaxial films grown by molecular beam epitaxy shows good agreement with the proposed phase diagram.