The relationship between quantum transport and microstructure evolution in carbon-sheathed Pt granular metal nanowires

The carbon-sheathed Pt nanowires fabricated by focused ion beam induced deposition were Pt grains in a Ga-doped carbon matrix. The dimensions of the Pt quantum dots and the intergrain coupling strength were modified through annealing the nanowires, and therefore our investigation demonstrates a tunable 'quantum metal' system by experiment via adjusting both the effects of electron-electron (e-e) interaction and the quantum interference. At low temperatures, the as-deposited samples display a root T temperature dependence of resistivity, while the 500 degrees C annealed samples exhibit a ln(T) temperature dependence of conductivity. For the 900 degrees C annealed samples, the conductivity was enhanced by one order of magnitude, accompanied by a metallic temperature dependence of resistivity and a negative magnetoresistance. The interesting transitions from e-e interactions to local voltage fluctuations, from electron localization to delocalization, from tunneling transport between isolated Pt grains to diffusive transport in continuously conductive metal, and from weak antilocalization with spin-orbital scattering to weak localization, are discussed with reference to the evolution of the sample microstructures. The results and discussions may be valuable for understanding how the microstructures influence the manner of electron transport through controlling the intergrain coupling strength, intragrain confinements, and the degree of disorder.