First attemt has been done in growing epitaxially the heterostructure YBaCuO/ LnBaCuO (Ln=Er, Nd) films. As an extended demonstration of the heterostructure, the superlattice structure was grown. The trilayered perovskite structure, however, was missing in the film (thinner than a few nm) grown on SrTiO3 substrates regardless of their crystal orientation. MgO was a promising material which can solve this problem.
