Electrical conductivity of a single Au/polyaniline microfiber

We report the measurements of conductivity, I - V curve, and magnetoresistance of a single Au/polyaniline microfiber with a core-shell structure, on which a pair of platinum microleads was attached by focused ion beam. The Au/polyaniline microfiber shows a much higher conductivity ( ∼ 110 S ∕ cm at 300 K ) and a much weaker temperature dependence of resistance [ R ( 4 K ) ∕ R ( 300 K ) = 5.1 ] as compared with those of a single polyaniline microtube [ σ RT = 30 - 40 S ∕ cm and R ( 4 K ) ∕ R ( 300 K ) = 16.2 ]. The power-law dependence of R ( T ) ∝ T − β , with β = 0.38 , indicates that the measured Au/polyaniline microfiber is lying in the critical regime of the metal-insulator transition. In addition, the microfiber shows a H 2 dependent positive magnetoresistance at 2, 4, and 6 K .