Magnetoresistance of a self-assembled polyaniline single microfiber

Abstract

Polyaniline microfibers were synthesized by using a self-assembly method. The electron hopping transport in this partially dedoped polyaniline single fiber showed typical bias-dependent characteristics. The magnetoresistance properties of the fiber were systematically investigated. In this microfiber, both positive and negative magnetoresistances were observed. An apparent positive magnetoresistance (> 1%) was found at 50 K. This temperature is much higher than previous reports of single or few nanofiber/tubes bundles (< 10 K). With the increase in temperature, the positive magnetoresistance was converted to the negative magnetoresistance where the transition happened at ca. 90 K. Moreover, the magnetoresistance was also sensitive to the applied bias. These observations could be explained by using the combination or competition of electron wave function shrinkage effect, quantum decoherence effect, as well as localized states coupling effect.