Strain enhancement of high-k dielectric response in (La/Sc)2 O3 and LaScO3 : an ab-initio study

We use density functional theory within the generalized gradient approximation to characterize the dielectric response of rare earth oxides: (La,Sc)2 O3 bixbyite, and LaScO3 perovskite. We focus on the role of strain on the phonon contribution of the dielectric constant and find that, contrary to the classical expectation based on the Clausius-Mossotti relation, tensile volumetric strain and volume-conserving bi- axial strain on the order of +/-1% can lead to an increase in dielectric constant of up to 20%. The insight into the atomic mechanisms responsible for these effects and the quantitative results in this paper can contribute to the development and understanding of high-{\kappa} materials.