A method to determine the orientation of superconductor surfaces and thin layers

Abstract

If it is easy to determine the orientation of a superconducting surface of thin layer haying grains greater than one micrometer size in basing on the high polarization anisotropy in Micro-Raman Spectroscopy, it is not the case when there is no grain on the surface. In this paper, we suggest a method to overcome this difficulty by screening the surface with a rotation reaching the angle giving the highest contrast in Raman polarization. With a previous calibration of polarized Raman intensity of known oriented single crystal versus the angle, the orientation of the surface can then be determined. Micro-Raman spectroscopy also helps to check the homogeneity of the surface and to determine the oxygen content in the case of Y-Ba-Cu-O series. This technique is also useful to determine the epitaxial quality and the micro-structure of layers at different thicknesses as well as to detect chemical and structural modifications at the interface. The method will be applied to thin layers and surfaces of YBa 2Cu 3O x on various substrates like ZrO 2, SrTiO 3, BeO and MgO and can be extended to Bi-Sr-Ca-Cu-O and Tl-Ba-Ca-Cu-O thin films.