Strain dependence of the electronic phase transition in epitaxial La$_{1/3}$Sr$_{2/3}$FeO$_{3}$ films*

The electronic transport properties of La$_{1/3}$Sr$_{2/3}$FeO$_{3}$ thin films were experimentally investigated as a function of epitaxial strain. In bulk, this compound exhibits a first-order electronic phase transition at 198 K accompanied by an abrupt change in resistivity. In order to investigate how different epitaxial strain states affect the abruptness and temperature of the transition, thin La$_{1/3}$Sr$_{2/3}$FeO$_{3}$ films were grown using molecular beam epitaxy on SrTiO$_{3}$ DyScO$_{3}$ and (La,Sr)(Al,Ta)O$_{3}$ imparting $+$0.9{\%} $+$1.8{\%} and -0.05{\%} strain, respectively. The transition temperatures were determined through resistivity measurements as well as synchrotron x-ray diffraction of (4/3 4/3 4/3) peaks, which are a direct signature of an additional ordering below the transition temperature. We find that the transition temperature measured through resistivity and the integrated intensity of the (4/3 4/3 4/3) peaks are in excellent agreement. The variation in transition temperature and the abruptness of the transition will be presented for the films grown on the various substrates.