Nanowall pinning for enhanced pinning force in YBCO films with nanofabricated structures

• High resolution lithography techniques to fabricate artificial pinning centres in high temperature superconductors.
• Enhanced critical currents of YBCO films with engineered nanofabricated structures.
• Controlled nano-walls with weakened superconductivity acting as strong pinning centres.

High resolution nanofabrication tools (Focused Ion Beam and Electron Beam Lithography) have been used to fabricate nano-metric milled structures in high critical current YBCO thin films able to further increase their vortex pinning capabilities. We have demonstrated that pinning forces at 77 K and 3 T are increased by a 70–80% by proper nanostructure designs. Model systems with linear trenches and triangular blind antidots of different sizes, distribution and density have been generated and studied. We demonstrate that specific milled nanostructures can increase the total current through the system at expenses of a limited decrease of cross section. We have identified the length of fabricated nano-walls as the main parameter controlling the pinning potential of nanostructures and thus defined the optimised milling conditions and nanostructure morphology to maximise pinning efficiency.