Direct-write, focused ion beam-deposited, 7 K superconducting C-Ga-O nanowire

We have fabricated C-Ga-O nanowires by gallium focused ion beam-induced deposition from the carbon-based precursor phenanthrene. The electrical conductivity of the nanowires is weakly temperature dependent below 300 K and indicates a transition to a superconducting state below T(c)=7 K. We have measured the temperature dependence of the upper critical field H(c2)(T) and estimate a zero temperature critical field of 8.8 T. The T(c) of this material is approximately 40% higher than that of any other direct write nanowire, such as those based on C-W-Ga, expanding the possibility of fabricating direct-write nanostructures that superconduct above liquid helium temperatures. (C) 2010 American Institute of Physics. [doi:10.1063/1.3458863]