  Transport in ultrathin films of LaNiO3 evolves from a metallic to a strongly
localized character as the film's thickness is reduced and the sheet resistance
reaches a value close to h/e2, the quantum of resistance in two dimensions. In
the intermediate regime, quantum corrections to the Drude low- temperature
conductivity are observed; they are accurately described by weak localization
theory. Remarkably, the negative magnetoresistance in this regime is isotropic,
which points to magnetic scattering associated with the proximity of the system
to either a spin glass state or the charge ordered antiferromagnetic state
observed in other rare earth nickelates.
