Thickness dependence of the superconducting transition temperature of La2-xSrxCuO4 films

A model of the strain effect on the transition temperature T-c of supercond ucting films is presented. Details are given for previously published resul ts on the thickness dependence of T-c in the (001) La1.85Sr0.15CuO4 films. A key role is played by the strain resulting From lattice mismatch between the film and the substrate, which is responsible for the behavior of T-c. C alculations show that the values of T-c of the films on SrLaAlO4 substrates under compressive strain are always higher than those on SrTiO3 under tens ile strain. As the thickness is reduced, the films grown on SrTiO3 substrat es exhibit a rapid reduction of T-c, whereas the T-c increases on SrLaAlO4 substrates. The theoretical results are in good agreement with experiments.