Strong pinning at high growth rates in rare earth barium cuprate (REBCO) superconductor films grown with liquid-assisted processing (LAP) during pulsed laser deposition

Abstract

<jats:title>Abstract</jats:title> <jats:p>We present a simple liquid-assisted processing (LAP) method, to be used <jats:italic>in situ</jats:italic> during pulsed laser deposition growth to give both rapid growth rates (50 Hz deposition leading to &gt;250 nm min<jats:sup>−1</jats:sup> with a single plume) and strong pinning (improved ×5–10 at 30 K and below, over plain standard YBCO films grown at similar rates). Achieving these two important features <jats:italic>simultaneously</jats:italic> has been a serious bottleneck to date and yet for applications, it is critical to overcome it. The new LAP method uses a non-stoichiometric target composition, giving rise to a small volume fraction of liquid phase during film growth. LAP enhances the kinetics of the film growth so that good crystalline perfection can be achieved at up to 60× faster growth rates than normal, while also enabling artificial pinning centres to be self-assembled into fine nanocolumns. In addition, LAP allows for RE mixing (80% of Y with 20% of Yb, Sm, or Yb + Sm), creating effective point-like disorder pinning centres within the rare earth barium cuprate lattice. Overall, LAP is a simple method for use in pulsed laser deposition, and it can also be adopted by other <jats:italic>in situ</jats:italic> physical or vapour deposition methods (i.e. MOCVD, evaporation, etc) to significantly enhance both growth rate and performance.</jats:p>