  Nickelate films have recently attracted broad attention due to the
observation of superconductivity in the infinite layer phase of
$Nd_{0.8}Sr_{0.2}NiO_2$ (obtained by reducing Sr doped $NdNiO_3$ films) and
their similarity to the cuprates high temperature superconductors. Here we
report on the observation of a new type of transport in oxygen poor
$Nd_{0.8}Sr_{0.2}NiO_{3-\delta}$ films. At high temperatures, variable range
hopping is observed while at low temperatures a novel tunneling behavior is
found where Josephson-like tunneling junction characteristic with serial
resistance is revealed. We attribute this phenomenon to coupling between
superconductive (S) surfaces of the grains in our Oxygen poor films via the
insulating (I) grain boundaries, which yields SIS junctions in series with the
normal (N) resistance of the grains themselves. The similarity of the observed
conductance spectra to tunneling junction characteristic with Josephson-like
current is striking, and seems to support the existence of superconductivity in
our samples.
