Local Grain Orientation and Strain in Polycrystalline YBa\u3cem\u3e\u3csub\u3e2\u3c/sub\u3e\u3c/em\u3eCu\u3cem\u3e\u3csub\u3e3\u3c/sub\u3e\u3c/em\u3eO\u3cem\u3e\u3csub\u3e7−δ\u3c/sub\u3e\u3c/em\u3e Superconductor Thin Films Measured by Raman Spectroscopy

Abstract

We report direct measurements of local grain orientation and residual strain in polycrystalline,C-axis oriented thin YBa2Cu3O7−δ superconducting films using polarized Raman spectroscopy. Strain dependence of the Ag Raman active mode at 335 cm−1 was calibrated and used to measure local strain in the films. Our data showed that high quality films are associated with the connected path of uniform grain orientation (single crystal-like) across the film and uniform residual strain in the range of −0.3%. Nonuniform grain orientation or high angle grain boundaries and nonuniform local strains were associated with low quality films