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A reasonable modification of an established phenomenological model is developed to investigate the recent report on sign reversal of magnetoresistance (MR) in 99.95% La0.7Sr0.3MnO3(LSMO)−0.05% paraffin wax hybrid nanocomposite system. At zero external magnetic field (H), all the grain boundary (GB) domain walls (DWs) are assumed to remain pinned at the pinning well. Due to depinning of spin‐polarized DWs with H, a negative MR response is observed between 15 K and 300 K. The GB DWs, which are expected to be pinned with strong pinning strength at and below 10 K, have undergone spin‐flip tunneling, thereby increasing the resistance of the composite with H, i.e., positive MR. The strong pinning phenomenon associated with positive MR is analytically modeled using a skewed Gaussian distribution of pinning strength at and below 10 K.

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We have investigated the electrical and optoelectrical properties of a zinc oxide (ZnO):reduced graphene oxide (rGO) nanocomposite film prepared through the sol gel process on a glass substrate under dark and illumination conditions of light. The bandgap of the composite film is decreased from the pure ZnO nanofilm due to the formation of a Zn-O-C bond in the composite film. The linear behavior in the Current-Voltage curve is attributed to Ohmic contact between ZnO and rGO grains. The photocurrent of the composite film is found to increase with an increase in light intensity having two different slopes, indicating an enhancement of the mobility of carriers and dissociation rate of excitons. The observed decrement of the impedance value with the intensity of light may be due to the flow of charge carriers and the presence of the light dependent relaxation process in the system. Nyquist plots have been fitted using a parallel combination of grain boundary resistances and grain boundary capacitance at different intensities of light. The relaxation frequency is observed to shift towards the high frequency regime. Carrier transit time has been calculated from relaxation frequency showing opposite behavior with the intensity of light. These results indicate the higher generations of photogenerated carriers at the interface between rGO and ZnO grains and an enhancement of the charge transport process due to the increment of the mobility of charge carriers in the system.