Large polarization and dielectric response in epitaxial SrZrO3 films

Abstract

First-principles calculations are performed to investigate the ferroelectric and dielectric properties of (001) epitaxial SrZrO₃ thin films under misfit strain. A rich phase diagram is predicted. By condensing the polar instability, the ferroelectric Pmc2₁ and Ima2 phases can coexist under tensile strain (about 3.7%–5.2%/5.7%). Combining in-plane ferroelectric (FE_xy) and out-of-plane in-phase antiferrodistortive (IAFD_z) modes, another new Pmc2₁ state (P > 56 μC cm⁻²) occurs with increase in the tensile strain. The paraelectric I4/mcm and ferroelectric P4mm phases emerge around −3.2%/−3.7% and −6.4%/−7.4% compressive strain, respectively. The former exhibits an intense out-of-plane dielectric response, while the latter possesses a rather large polarization (∼110 μC cm⁻²). The large polarization and dielectric response are discussed in relationship to strain-driven structural distortion.