  The charge transport properties of single superconducting tin nanowires,
encapsulated by multiwalled carbon nanotubes have been investigated by
multi-probe measurements. The multiwalled carbon nanotube protects the tin
nanowire from oxidation and shape fragmentation and therefore allows us to
investigate the electronic properties of stable wires with diameters as small
as 25 nm. The transparency of the contact between the Ti/Au electrode and
nanowire can be tuned by argonion etching the multiwalled nanotube. Application
of a large electrical current results in local heating at the contact which in
turn suppresses superconductivity.
