Effects of epitaxial strain on the growth mechanism in (formula presented) thin films in (formula presented) superlattices

We report on the growth mechanism of (formula presented) Our study is based on an analysis of ultrathin (formula presented) (YBCO) layers in c-axis-oriented (formula presented) superlattices. We have found that the release of epitaxial strain in very thin YBCO layers triggers a change in the dimensionality of the growth mode. Ultrathin epitaxially strained YBCO layers with thickness below 3 unit cells grow in a block-by-block two-dimensional mode that is coherent over large lateral distances. Meanwhile, when the thickness increases and the strain relaxes, layer growth turns three-dimensional, resulting in rougher layers and interfaces.