Magnetic Granularity in Iron-Based Superconducting Films on RABiTS Templates

Abstract

Iron-based superconductors are a popular candidate in the search for affordable superconductors for high-field applications. In particular, the relaxed texture requirements resulting from a less severe reduction of the currents across grain boundaries fuel hope that films deposited on RABiTS with simple buffer layer architectures could enable cheap coated conductors. We investigated the local current flow of iron-based superconductors deposited by PLD on RABiTS templates by means of scanning Hall probe microscopy. Local current densities exceeding 1 MA cm−2 were observed, however, granularity still seems to be an issue. Transmission electron microscopy images and analysis by transmission Kikuchi diffraction show that the out-of-plane orientation of underlying Ni-W grains in the substrate has a severe impact on the growth of the films. We assessed the granularity by deriving the distribution density of the local current densities in order to compare it quantitatively to the granularity of YBCO based coated conductors.