Effect of epitaxial strain on the optical properties of NaOsO3

Abstract

We study the electronic and optical properties of NaOsO3 under epitaxial strain using first principles methods. Structural optimization shows important changes with strain in the structural parameters such as the OsO bond lengths and the octahedral rotation angles. The key change in the electronic structure is the band gap, which increases with compressive epitaxial strain and decreases with tensile strain. The computed optical absorption coefficient is more or less isotropic for the unstrained structure for light polarization along the three crystallographic directions, but for the strained structure, it is enhanced if the light polarization is along a compressed crystallographic direction due to strain. This is explained in terms of the admixture of Os (p) orbitals with the Os (d) states that form the valence and the conduction bands.