Anisotropic resistance change of La_0.7Sr_0.3MnO₃ thin films effected by in-plane axial strain

Abstract
Thin films of La_0.7Sr_0.3MnO₃ grown on (001) NdGaO₃ substrate using vertical hot wall Injection CVD reactor were investigated by means of standard fish-bellied beam inducing uniaxial compressive (or tensile) strain of the films. The measurements were carried out in current direction both parallel (longitudinal resistance R₁) and perpendicular (transversal resistance R₁) to the strain direction. The compression along [100], [110], [010] and [110] directions on films having 8 nm thickness showed the strong anisotropy of strain induced resistance change. The compression along [010] and [l10] directions caused the decrease of the film resistance while the compression along [100] and [110] directions increased this resistance. The maximum obtained relative resistance change was about 27% at strain 0.005. This effect appeared in both longitudinal and transversal directions of the electric current. The experimental results are discussed in terms of external strain influence on anisotropically strained La_0.7Sr_0.3 MnO₃ film lattice produced as a result of large mismatch between substrate and film lattice constants.