Tunable positive magnetoresistance of magnetic polyaniline nanocomposites

Tunable positive magnetoresistance (MR) of polyaniline (PANI) nanocomposites with different magnetic nanoparticles (Fe₃O₄ or CoFe₂O₄) have been prepared through the facile surface-initiated polymerization (SIP) method. The characterizations including Fourier transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM) indicate that the magnetic nanoparticles were successfully coated by PANI. A quasi 3D variable range hopping (VRH) mechanism was observed in the magnetic PANI nanocomposites through Mott VRH model. The effects of magnetic field and magnetic nanoparticle on the charge carrier’s behavior were studied by the wave function shrinkage model. The localization length and average hopping length decrease with increasing magnetic field, while the density of state at the Fermi level increases with increasing magnetic field. The enhanced dielectric property and magnetic property of the magnetic PANI nanocomposites were reported as well. Graphical abstract: Magnetic polyaniline nanocomposites with tunable positive magnetoresistance. [Figure not available: see fulltext.].