Phase Transition from a Spin-Glass Metal to Superconductor in La2-xSrxCuO4 (x<0.05) Single Crystalline Films by Epitaxial Strain

Epitaxial growth of films is an effective way to induce high anisotropic pressure on films. In this work we have grown La$_{2-x}$Sr$_{x}$CuO$_{4}$ (LSCO) (0.03$<$x$<$0.05) films, having metallic behavior in bulk, by liquid phase epitaxy technique along the $<$100$>$ direction. For the desired kind of strain we have chosen overdoped LSCO ($\sim $x=0.19) as the substrate. We observed that the resistance versus temperature measurement, in a configuration where the film and substrate are in series, shows a two-step superconducting transition. We suggest that the other transition, which does not coincide with the T$_{c}$ of substrate, is due to superconductivity in film. The T$_{c}$ of the films with x=0.034, 0.040 and 0.045 are found to be 25K, 30K and 34K, respectively. Where as the x=0.0 film is not superconducting. In our work we have shown possible transition of a spin-glass metallic phase to a superconducting phase in LSCO (0.03$<$x$<$0.05) films induced by epitaxial strain.