  Superconducting nanowires can be synthesised in high-throughput chemical
routes and hold great promise as a low-dissipative material for superconducting
devices. The applicability of superconducting nanowires, however, has been
limited due to the lack of an adequate method to fit the nanowires into given
electronic circuits. One of the biggest obstacles is to connect metal terminals
to superconducting nanowires in order to establish electric contacts. One
attractive method to surmount this difficulty is to synthesise superconducting
nanowires directly upon metal terminals such that the nanowires electrically
contact the metal surface. Here we demonstrate that this can be achieved by
electrodeposition in molten salts. The 39-K superconductor magnesium diboride
(MgB2) is electrodeposited to metal surfaces in the form of highly crystalline
nanowires. The MgB2 nanowires achieve extensive electric contacts with the
metal surfaces. The MgB2 nanowires carry high densities of supercurrents that
are comparable to bulk materials. This approach to the electrodeposition of
MgB2 nanowires provides a solution to one of the major challenges preventing
practical applications of superconducting nanowires.
