Epitaxial superconductors on rolling-assisted biaxially-textured substrates (RABiTS): A route towards high critical current density wire

Fabrication of epitaxial, high-J_c, biaxially aligned YBCO thick films on rolling-assisted biaxially-textured substrates (RABiTS) is summarized. The RABiTS technique utilizes standard thermomechanical processing to obtain long lengths of flexible, biaxially oriented substrates with smooth surfaces (rms ∼ 50 nm). The strong biaxial texture of the metal (in-plane 6-7° FWHM) is conferred to the superconductor by deposition of intermediate metal and/or oxide layers which serve both as a chemical as well as a structural buffer. Epitaxial YBCO films grown using laser ablation on RABiTS™ have critical current densities exceeding 10⁶ A cm^-2 at 77 K in zero-field and have field dependences similar to epitaxial films on single crystal ceramic substrates. The texture of the base metal has been achieved in lengths over 1 m and scaleable techniques are being pursued to deposit epitaxial multilayers. Deposited conductors made using this technique offer a potential route for the fabrication of long lengths of high-J_c wire capable of carrying high currents in high magnetic fields and at elevated temperatures.