Anisotropic transport and Negative Resistance in a polycrystalline metal-semiconductor (Ni-TiO2) hybrid

Abstract: We investigate anomalous electrical transport properties of a Ni-TiO2 hybrid system displaying a unique nanostructured morphology. The system undergoes an insulator to metal transition below 150 K with a low temperature metallic phase that shows negative resistance in a four-probe configuration. Temperature dependent transport measurements and numerical modelling show that the anomalies originate from the dendritic architecture of the TiO2 backbone interspersed with Ni nanoparticles that paradoxically renders this polycrystalline, heterogeneous system highly anisotropic. The study critiques inferences that may be drawn from four-probe transport measurements and offers valuable insights into modelling conductivity of anisotropic hybrid materials.