Epitaxially induced defects in Sr- and O-doped La₂CuO₄ thin films grown by MBE: Implications for transport properties

In this paper, the critical role played by various types of defects and strain relaxation mechanisms in high-Tc thin films is highlighted and illustrated with examples. The defects are essential for providing adequate diffusion channels for oxygen ingress during the cooling step in c-axis thin films. The operation of strain relaxation mechanisms necessitated by the lattice mismatch between film and substrate can impose a compressive or tensile biaxial pressure, which either increases or reduces the critical temperature.