Magnetoresistive Polyaniline Nanocomposites Incorporating Nickel Ferrite-Modified Carbon Nanotubes

Abstract

In this work, nickel ferrite/carbon nanotubes–polyaniline (NiFe2O4@CNTs-PANI) nanocomposites with positive magnetoresistance (MR) phenomenon was obtained by the hydrothermal method combined with the surface-initiated polymerization (SIP) method. The NiFe2O4@CNTs-PANI nanocomposites’ resistivity decreased as the temperature increased, exhibiting typical semiconductor behavior. This temperature-dependent resistivity revealed a quasi-three-dimensional (3D) variable range hopping (VRH) charge carrier transport mechanism. Based on the wave function shrinkage model, its positive MR was studied. It was found that the localization length (a0) and average hopping distance (Rhop) were decreased with increasing magnetic field strength, indicating the reduction in the hopping probability of the charge carrier, which was beneficial for the positive MR. Meanwhile, the values of a0 and Rhop were decreased with increasing NiFe2O4@CNTs loading, expressing a nanofiller loading-dependent behavior.