Effect of substrate strain on lattice structure, electrical resistivity, and optical conductivity of thin films grown on

In this study, we investigated the lattice structure, electrical resistivity, and optical conductivity of Nd0.5Sr0.5MnO3 thin films grown on SrTiO3 (001) and SrTiO3 (011) substrates. The thin film on SrTiO3 (001) experiences isotropic tensile strain and shows characteristics of the semiconducting ground state. On the other hand, the thin film on SrTiO3 (011) experiences anisotropic tensile strain, which means that one of the two in-plane lattice axes is fixed by the substrate lattice and the other axis is relaxed. The thin film shows the insulator–metal phase transition at 220 K and characteristics of the charge-ordered insulating ground state below 150 K. By comparing the single crystal data of the lattice along with the resistivity and optical conductivity, we suggest that the substrate strain affects the electronic structure as well as the carrier dynamics of the Nd0.5Sr0.5MnO3 thin films. We propose the possible ground states formed in the thin films.