Tunneling mechanism through the nonlinear electrical transport in Co/CoO particles with core-shell nanostructure

We investigate the nonlinear electrical transport as a function of temperature in Co/CoO nanoparticles having core-shell nanostructure. Nanoparticle was synthesized by sol-gel citrate precursor technique where core-shell nanostructure is confirmed by the high resolution Transmission Electron Microscopy. Current–voltage (I–VI–V) characteristics are measured over the temperature range 20–295 K. I–VI–V curve exhibits ohmic behaviour at 295 K. Nonlinear electrical transport is observed at low temperature (T  ) for T⩽275 KT⩽275 K. Electrical transport properties have been interpreted in terms of tunneling mechanism where tunneling between ferromagnetic Co nanoparticles takes place through the antiferromagnetic CoO layer. Analysis of dynamic conductance (G=dI/dVG=dI/dV) indicates that the inelastic tunneling via localized states of antiferromagnetic CoO layers is dominant in the transport mechanism at low temperature.