Negative giant magnetoresistance effect in single layered superparamagnetic polymer nanocomposite structures of poly(vinyl alcohol)-polyaniline/bismuth ferrite

Superparamagnetic polyaniline/bismuth ferrite (PANI/BFO) nanocomposite powder is synthesized through an in situ sol-gel polymerization method and it is embedded in non-magnetic poly(vinyl alcohol) (PVA) matrix to fabricate high performance flexible films. The interaction between PANI/BFO filler and PVA matrix and hence the formation of composite is identified through XRD and it is further confirmed through FTIR spectra. Vibration sample magnetometry (VSM) studies ensure the superparamagnetic nature of the composite films. The magnetoresistance measurements are made at room temperature for various current values from which it is observed that the samples exhibit a negative giant magnetoresistance (GMR) effect. The variation of GMR from 21% to 66% with filler concentration and also the non-ohmic V-I characteristics of the composite films are reported.