YBa2Cu3O7 nanobridges fabricated by direct-write electron beam lithography

Abstract
A direct method for nondamaging, nanometer‐scale patterning of high Tc superconductor thin films is presented. We have fabricated superconducting nanobridges in high‐quality, epitaxial thin‐film YBa2Cu3O7 (YBCO) by combining direct‐write electron beam lithography and an improved aqueous etchant. Weak links with both length and width dimensions less than 20 nm have exhibited critical currents at 77 K of 4–20 μA and IcRn products of 10–100 μV which compare favorably with results for other YBCO junction technologies. We have used this technique in the fabrication of a shock‐wave pulse former as an initial demonstration of its applicability to monolithic superconductive electronics.