Electrical transport properties of nanocrystalline zinc ferrite

Electrical transport properties of nanocrystalline zinc ferrite were investigated in the temperature range 77⩽T⩽300 K, applying magnetic field upto 1 T in the frequency range 20 Hz–1 MHz. The DC conductivity follows a simple hopping type charge transport. The DC magnetoresistivity of the samples is negative, which has been explained by using tunnelling theory of magnetoresistivity. The AC conductivity was found to follow the universal dielectric response σ′(f)∝Tnfs. The value of s is found to be weak temperature dependent for T<200 K, but shows a decreasing trend with temperature for T>200 K. The temperature exponent, n strongly depends on frequency and range of temperature. The dielectric permittivity increases with decreasing particle size, which has been interpreted by the Maxwell Wagner capacitor model. Magnetic field dependence AC conductivity shows a positive variation. A firm theoretical explanation of magnetic field dependence of AC conductivity is still lacking. The different physical parameters were calculated from the experimental data.