Strain Relaxation in Thin Films of La$\text{}_{1.85}$Sr$\text{}_{0.15}$CuO$\text{}_{4}$ Grown by Pulsed Laser Deposition

X-ray diffraction, resistivity, and susceptibility measurements are used to examine the effects of film thickness d (from 17 to 250 nm) on the structural and superconducting properties of La$\text{}_{1.85}$Sr$\text{}_{0.15}$CuO$\text{}_{4}$ films grown by pulsed laser deposition on SrLaAlO$\text{}_{4}$ substrates. For each d the film sgrow with a variable strain, ranging from a large compressive strain in the thinnest films to a negligible or tensile strain in thick films. Our results indicate that the tensile strain is not caused by the off-stoichiometric layer at the substrate-film interface. Instead, it may be caused by the extreme oxygen deficiency in some of the films.