Nanostructure Investigations of Nonlinear Differential Conductance in   NdNiO$_3$ Thin Films
  Transport measurements on thin films of NdNiO$_3$ reveal a crossover to a regime of pronounced nonlinear conduction below the well-known metal-insulator transition temperature. The evolution of the transport properties at temperatures well below this transition appears consistent with a gradual formation of a gap in the hole-like Fermi surface of this strongly correlated system. As $T$ is decreased below the nominal transition temperature, transport becomes increasily non-Ohmic, with a model of Landau-Zener breakdown becoming most suited for describing $I(V)$ characteristics as the temperature approaches 2~K. 
Will J. Hardy, Heng Ji, Evgeny Mikheev, Susanne Stemmer, and Douglas   Natelson
cond-mat.str-el cond-mat.mes-hall