Raman tensor and domain structure study of single-crystal-like epitaxial films of CaCu3Ti4O12 grown by pulsed laser deposition

The local domain structure of a strain free, 150 nm thick, epitaxially grown single crystalline thin film of CaCu3Ti4O12 is probed by polarized Raman spectroscopy. The polarization dependence of the Raman intensities of the observed bands as a function of varying angle between the domain axes and the polarization vector of the scattered laser photon is measured. Theoretical formulations involving the Raman tensor are presented, which enable determination of the domain structure from the observed polarized Raman spectra, and a single-crystal-like domain structure is found. The Raman tensor elements and domain orientation direction were determined by fitting the observed Raman intensities with theoretical calculations and by carrying out Raman mapping of the film. Our data show an absence of twin domain structure and twin domain boundaries in the single-crystal-like epitaxial thin films of CaCu3Ti4O12.