Impact of Calcium Doping of YBa₂Cu₃O_7-δ Multilayer Thin Films on the Flux Pinning Landscape at 65–5 K, 0–9 T for Various Applications

An important research goal in the applications of high temperature superconductor YBa ₂ Cu ₃ O _7-δ (YBCO) thin films is increasing both the critical current density and also the isotropic nature of the film. YBCO is inherently anisotropic due to its layered perovskite structure. The critical current density of YBCO thin films is enhanced by increasing the flux pinning sites in the film by the addition of insulating nano-phase materials, such as BaZrO ₃ (BZO) nanorods, which are also anisotropic in nature. Using a multilayer pulsed laser deposition technique has been shown to produce films with inclusions that are more isotropic in nature. However, the defective BZO nanorod interface, resulting from its lattice mismatch with YBCO, prevents obtaining optimum pinning force. This research explores the effect of Ca doped YBCO space layers in the multilayer composite film, on the BZO nanorod/YBCO interface, over a wide range of conditions of 65–5 K and 0–9T that are suitable for various applications. The interplay of combining these three variables: BaZrO ₃ addition to YBCO, multilayer film growth resulting from varying pulsed laser deposition conditions, and employing calcium doped YBCO space layers, and the resulting impact on film microstructures and superconducting properties, will be presented.