XRD and TEM characterization of cuprate thin films epitaxially grown on SrTiO3 (001) vicinal surfaces

We report X-ray diffraction and transmission electron microscopy of YBa2Cu3 O7 (YBCO) and NdBa2Cu3O7 (NBCO) thin films grown by pulsed laser deposition on SrTiO3 (0 0 1) vicinal surfaces (SrTiO3, STO). Most YBCO films tend to grow parallel to the geometrical surface: YBCO (0 0 1) planes are parallel to the substrate surface rather than to STO (0 0 1) planes. On the contrary , NBCO tends to follow the STO (0 0 1) planes. The tetragonal to orthorhomb ic phase transition upon cooling induces twinning in both materials. The tw ins appear to have better defined interfaces in YBCO than in NBCO. While th e two twin variants [1 1 0] and [1 1 0] are present in YBCO, only one occur s in NBCO films. This selectivity of twin orientation might be useful in de vice applications. (C) 2001 Elsevier Science B.V. All rights reserved.