The growth of (001) YBa 2Cu 3O (7−δ) thin films on (001) MgO by pulsed organo—metallic beam epitaxy with controlled in-plane orientation

Abstract

Thin films of (001) YBCO are grown on epitaxially polished (001) MgO by pulsed organo–metallic beam epitaxy. The in-plane orientation of the film is controlled by the thickness of a BaO layer, grown in situ, prior to the YBCO growth. For thin BaO layers (<≈0.7×10 15 Ba cm −2) the films grow [110]YBCO|[100]MgO. For thick BaO layers (>≈1.1×10 15 Ba cm −2) the films grow [100]YBCO|[100]MgO. For YBCO films grown with thin BaO layers (>≈0.7 times 10 15 Ba cm −2), ex situ, low energy Ar + ion sputtering of the MgO surface prior to film growth will also induce a change of in-plane orientation from [110]YBCO|[100]MgO on epitaxial polished MgO to [100]YBCO|[100]MgO on Ar + sputtered MgO. A mechanism that relates the change in YBCO in-plane orientation to a change in the structure of the initial BaO layers with BaO thickness is described.