Investigation of electronic and magneto-transport properties in Nd doped Pr_(0.67)Sr_(0.33)MnO_3 perovskite manganite

摘要

The effect of Nd substitution on electrical and magneto-transport transport properties in Pr_(0.67-x)Nd_xSr_(0.33)MnO_3(x = 0.02, 0.04, 0.06) synthesized using nitrate route have been investigated. Rietveld refinement of XRD data reveals that all the samples crystallize into orthorhombic crystal structure with Ibmm space group. The substitution of Nd decreases the lattice parameters and unit cell volume because of smaller ionic radii of Nd~(3+) compared to Pr~(3+). For all samples, temperature dependent electrical resistivity plot shows a clear metal-insulator transition at T_(MI) and its shifting monotonically towards high temperature side has been seen with Nd~(3+) substitution and also application of magnetic field. The metallic region (TT_(MI) (insulating region) the small polaron hopping (SPH) model and variable range hopping (VRH) are dominant. Significant negative magnetoresistance (MR) observed at low temperature is explained due to inter-grain spin polarized tunneling across grain boundary and domain contribution. This has been confirmed by fitting field dependent MR isotherms using scaling law suggesting a linear variation below T_(MI) and quadratically above T_(MI).