Electrical behavior of sol-gel prepared Nd0.67Sr0.33MnO3 manganite system

With a view to understand the conduction mechanism in these materials, the electrical conductivity of all these materials was measured over a temperature range 80-300 K and in a magnetic field upto 7 T and the data were analyzed by using several theoretical models. It has been observed that the metallic (ferromagnetic) part of the temperature-dependent resistivity (ρ) curve (below TP) fits well with ρ(T)=ρ0+ρ2T2+ρ4.5T4.5, indicating the importance of grain/domain boundary effects and electron-magnon scattering processes in the conduction of these materials. On the other hand, in the high temperature (T>TP) paramagnetic insulating regime, the adiabatic small polaron and VRH models fit well, thereby indicating that polaron hopping might be responsible for the conduction mechanism.