Preparation of Narrowed ${\rm YBa}_{2}{\rm Cu}_{3}{\rm O}_{7-{\rm x}}$ Nanobridges Down to 30 nm With Reduced Degradation

Abstract

We have established the new method of fabricating high-c YBa 2 Cu 3 O 7 x (YBCO) nanobridges with high reproducibility. Nanobridges ranging in 30-400 nm wide were formed by using electron beam lithography. An ultra thin film of 2-3 nm-thick insulative YBCO was deposited after nanobridge formation for recovering the damaged films occurred in the process.The critical current density c was approximately 620 MA cm 2 at 4.2 K in a width of 30 nm bridges, and increased by about two orders of magnitude in the different widths of c . The critical temperature c was 87 K, about the same as c of the film. The current-voltage characteristics showed a different curve from the conventional flux-flow type as the widths have been narrowed. Nanobridges developed in this study are expected to the applications for nano-SQUIDs or the optical input/output interfaces in single-flux-quantum circuits.

Ratchet Effect of Single Vortex Motion in Superconducting Asymmetrical Nanobridges

“…The electron beam lithography conditions are described elsewhere. 12) The microfabrication process often degrades the quality of YBCO films, 13) and thus the characteristics of nanobridges made under the same conditions show poor reproducibility. To overcome this degradation, we employed intermittent etching, using a cycle of 30 s etching and 90 s cooling to reduce the heating of the substrate.…”

Electrospinning of superconducting YBCO nanowires

“…Textiles techniques, such as dry spinning and solution spinning, yield YBCO fibers with relatively long lengths and large diameters in the micrometer range [13][14][15][16][17]. YBCO fibers with nanoscale diameters have been produced by focused ion beam [18], electron beam lithography [19], superlattice nanowire pattern transfer [20], and the sol-gel template process [21].…”