Growth of (110)-oriented epitaxial RBa 2Cu 3O 7− δ thin films and characterization with Raman spectroscopy

Abstract

High-quality superconducting (110) and (103)/(013)-oriented SmBa 2Cu 3O 7−δ thin films, with T c ≈ 90 K, have been grown on SrTiO 3 (110) substrates using pulsed laser deposition. The (110) orientatioon was obtained using a PrBa 2Cu 3O 7−σ buffer layer. The structure of the films has been investigated with atomic force microscopy (AFM) and Raman spectroscopy. AFM revealed a granular stripe-like surface morphology. The orientation of the films was determined from Raman measurements by comparing the intensity of the O(4) A g mode, the lineshape of the Ba A g mode and the intensity of the O(2)−O(3) out of phase A g mode taken in different polarization geometries. Faint B 3 g , B 3 g and oxygen defect modes of the SmBa 2Cu 3O 7−σ system were also resolved in the low temperature Raman spectra of the (110)-oriented film. A method for assessing the phase of the complex Raman tensor components of the A 1 g -like modes has been devised. It is illustrated for the case of the 114 cm −1 Ba A 1 g phonon: at 514.5 nm laser energy a phase difference of (2 ± 0.2) rad is found between the xx (yy) and zz Raman tensor components.