Multiband Optical Absorption Controlled by Lattice Strain in Thin-FilmLaCrO3

Experimental measurements and ab initio modeling of the optical transitions in strained G-type antiferromagnetic LaCrO(3) resolve two decades of debate regarding the magnitude of the band gap and the character of the optical absorption spectrum in the visible-to-ultraviolet (up to ∼5 eV) range in this material. Using time-dependent density functional theory and accounting for thermal disorder effects, we demonstrate that the four most prominent low-energy absorption features are due to intra-Cr t(2g)-e(g) (2.7, 3.6 eV), inter-Cr t(2g)-t(2g) (4.4 eV), and interion O 2p-Cr 3d (from ∼5 eV) transitions and show that the excitation energies of the latter type can be strongly affected by the lattice strain.