Strain and strain relaxation analysis of superconducting Ba(Fe$_{0.92}$Co$_{0.08}$)$_{2}$As$_{2}$ films on various substrates

We have grown high quality, optimally doped superconducting Ba(Fe$_{0.92}$Co$_{0.08})_{2}$As$_{2}$ films on SrTiO$_{3}$, (La, Sr)(Al, Ta)O$_{3}$, LaAlO$_{3}$, CaF$_{2}$ and BaF$_{2}$ substrates. The variation in lattice mismatch allows the study of epitaxial strain effects on the structural and transport properties of the films. Reciprocal space mapping has been employed for detailed strain and strain relaxation analysis of the Ba(Fe$_{0.92}$Co$_{0.08}$)$_{2}$As$_{2}$ films on the different substrates. We observed large substrate dependant changes in both in plane and out of plane lattice parameters. Furthermore, the crystallinity of the grown films, the lattice constant and lattice volume evolution with strain and strain relaxation were investigated, revealing an epitaxial strain and strain relaxation dependence on the superconducting transition temperature.