Optical absorption in epitaxial $La1−xSrxFeO3$ thin films Available to Purchase

We report the dependence of optical absorption on Sr concentration in $La1−xSrxFeO3$ (LSFO) (⁠$x≤0.4$⁠) perovskite thin films. Strained epitaxial films were deposited on $SrTiO3$ substrates using oxide molecular beam epitaxy. We find systematic changes in the optical absorption spectra with increasing x including a red-shift of transition energies and the increasing presence of a lower energy transition within the fundamental gap of pure $LaFeO3$⁠. These results serve as a demonstration of the complex manner in which absorption spectra can be altered in complex oxides via heterovalent A-site substitution.