  Emergent phenomena at interfaces between oxides and metals can appear due to
charge transfer and mass transport that modify the bulk properties. By coating
the metallic oxide LaNiO$_3$ by aluminium, we fabricated a junction exhibiting
a diode-like behaviour. At the equilibrium, the interface is insulating. The
metallic behaviour can be recovered by applying a voltage drop across the
junction in one polarity only. The electrical properties in direct and reverse
bias are investigated. The observed electro-resistive effect rises up to $10^5$
\% and can be interpreted in terms of (i) a spontaneous redox reaction
occurring at the interface and (ii) its reversal induced by charge injection in
direct bias.
