RAMAN-SPECTROSCOPY AS ANALYTICAL TOOL FOR THE LOCAL-STRUCTURE OF YBA2CU3OX THIN-FILMS

Raman spectroscopy is an ideal analytical tool for precise determinati on of crystallographic directions of epitaxial YBa2Cu3Ox (YBCO) thin f ilms. It can also be used for the the study of oxygen ordering and its dependence on growing conditions and subsequent treatments. Examples of Raman spectra of YBCO epitaxial thin films presented in this work p rovide evidence that microdomains of different oxygen arrangement (Ort ho-I, Ortho-II, T, T') may coexist within the same sample. Such a phas e separation occurs at a microscopic scale and is most clearly pronoun ced for underdoped samples. The transformation of local oxygen arrange ments with changes of oxygen content upon thermal treatment in vacuum and in air is also studied and discussed.