Nature of electrical hopping conduction and magnetotransport studies in the electron doped manganite Ca0.85Gd0.15MnO3

•Temperature and magnetic field dependent resistivity of Ca0.85Gd0.15MnO3 was studied.•Small polaron hopping (SPH) dominates above charge ordering temperature (TCOTCO).•Resistivity follows parallel combination of SPH and VRH model below TCOTCO.•Conductivity exhibited a variable range hopping (VRH) model at low temperature.•Magnetoresistance is governed by spin-polarized tunneling at grain boundaries.

The magnetotransport properties of Ca0.85Gd0.15MnO3 have been studied analyzing the temperature and magnetic field dependent resistivity. High temperature (T>TCOT>TCO: charge ordering temperature) conductivity has been found to be described by the non-adiabatic small polaron hopping (SPH) model. The manganite shows a parallel combination of SPH and variable range hopping (VRH) model below TCOTCO. VRH model fits the corresponding low temperature data. The field depended magnetoresistance (MR) has been investigated with a phenomenological model considering the spin-polarized tunneling. The field dependent MR in scaled coordinate collapses into single curve demonstrating the temperature-independent behavior.