Optical absorption in epitaxial La1-xSrxFeO3 thin films

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. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4794145]