Study of Grain Boundaries in YBCO Thin Films Using Microraman Spectroscopy

Abstract

AbstractMicroRaman spectroscopy allows to identify the presence of c| and c⊥ oriented grains in YBCO thin films. This is achieved by the observation of two Raman modes associated with the oxygen sublattice vibrations, ˜500 cm−1 and ˜338 cm−1. The relative intensity of these Raman modes is related to the presence of c⊥ and c⊥;. oriented grains. Using the high lateral resolution of the Raman microprobe (<1 μm) some needle shaped grains of the films were scanned. The different Raman parameters were analyzed, showing noteworthy transformations at the [c|;]/[c⊥] boundaries. In particular the Raman mode corresponding to the out of phase O (2)– O(3) in plane vibrations (˜338 cm−1) was found to be narrowed, which should account for a decoupling of the phonon with the electronic continuum.