Properties of strong-coupled MgB2 nanobridges fabricated by focused ion beam

Abstract

We have studied extremely strong-coupled MgB2 inter-grain nanobridges prepared by using focused ion beam. Nominal width and length of the bridges were 200 nm. The superconducting transition temperature and the critical current density of the bridges were the same as those of unpatterned film. Current-voltage (I-V) curves showed large excess currents, which is believed to be due to the flux-flow effect. Nevertheless, I-V curves showed substantial amount of Josephson coupling effect near T-c. The temperature-dependent critical current was I-c similar to (T-c - T)(1.5), similar to that of a thin superconducting film in Ginzburg-Landau theory. (C) 2009 Published by Elsevier B.V.