The key ingredient of high critical currents in a type-II superconductor is defect sites that pin vortices. Contrary to earlier understanding on nanopatterned artificial pinning, here we show unequivocally the advantages of a random pinscape over an ordered array in a wide magnetic field range. We reveal that the better performance of a random pinscape is due to the variation of its local density of pinning sites (LDOPS), which mitigates the motion of vortices. This is confirmed by achieving even higher enhancement of the critical current through a conformally mapped random pinscape, where the distribution of the LDOPS is further enlarged. The demonstrated key role of LDOPS in enhancing superconducting critical currents gets at the heart of random versus commensurate pinning. Our findings highlight the importance of random pinscapes in enhancing the superconducting critical currents of applied superconductors.
Bibliographical noteFunding Information:
This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. Nano patterning and morphological analysis were performed at Argonne''s Center for Nanoscale Materials (CNM) and the Electron Microscopy Center (EMC), which are supported by DOE, Office of Science, BES. L.R.T. and Z.L.X. acknowledge NSF Grant No. DMR-1407175 and NIU''s Nanoscience Graduate Fellowship.