Growth of CaCuO2 and SrxCa1 –xCuO2 epitaxial films on NdGaO3 substrates by pulsed laser deposition

Abstract

High quality epitaxial films of the ‘infinite layer’(IL) compound Sr_xCa_{1 –x}CuO₂(x= 0–1) have been grown by pulsed laser deposition on NdGaO₃(110) substrates, thus including the last member of this series CaCuO₂, for the first time, to our knowledge. The quality of films varied with the composition: higher quality films were obtained for x= 0 and 0.1. The experimental results have been explained by taking into account the lattice match between film and substrate: a better match results in a better film quality. A very good match is obtained on NdGaO₃ substrates for IL films with small or zero Sr content. Attempts to grow IL films were also carried out on SrTiO₃ and LaAlO₃ substrates. On SrTiO₃ substrates it was not possible to grow IL films in the absence of Sr, while on LaAlO₃ substrates no IL films could be grown at all. In the case of SrTiO₃, the lattice match is good only for Sr-rich films, while in the case of LaAlO₃, no good match can be obtained for any composition. Such substrate effects are not unexpected due to the importance of the substrate for the pseudomorphic stabilization of the otherwise unstable IL structure.