Raman scattering spectroscopy of Nd_1+xBa_2-xCu ₃O₇ coated conductors grown by pulsed laser deposition

We analyzed Nd_1+xBa_2-xCu₃O₇ (NdBCO) coated conductors grown at various substrate temperatures by using Raman spectroscopy. Epitaxial NdBCO films were deposited on ion beam assisted deposition yttrium stabilized zirconia (IBAD-YSZ) templates by pulsed laser deposition. Raman scattering spectroscopy shows that the NdBCO film grown at a relatively low substrate temperature of 750 °C contains some a-axis oriented grains as well as c-axis oriented grains and an excess cation disorder between Nd³⁺ ions and Ba²⁺ sites, which result in degradation of superconducting properties with critical temperature (T_c) of ∼83K and critical current density (J_c) of less than 1MAcm^-2 at 77K and self-field. The samples grown at higher temperatures ranging from 775 to 800 °C are found to have strong c-axis orientation with little cation disorder, and subsequently excellent superconducting properties with T _c of 88-90K and J_c of 1.2-1.8MAcm^-2 at 77K and self-field.