Investigation of hole-doping effect on structural, magnetic properties and magnetoresistance via Gd-site substitution by Pb in the layered manganite La 0.1 Gd 0.2−x Pb x Ca 1.2 Sr 0.6 Mn 2 O 7 (0 ≤ x ≤ 0.2)

In this work, the hole-doping double-layered manganites with formula La_1.0Gd_(0.2-x)Pb_xCa_1.2Sr_0.6Mn_2O_7 ( x = 0, 0.1, and 0.2) are prepared by the solid-state reaction route and experimentally characterized. The samples' crystallization into a tetragonal structure with an I4/mmm space group was confirmed by Rietveld refinement results of the XRD diffraction patterns using the FullProf software. The results were thoroughly studied after it was discovered that the cell parameters were decreasing. The structure was granular and porous, with grains that resembled spheres, according to micrographs obtained using a scanning electron microscope (SEM). Fourier-transform infrared (FTIR) analysis shows that our samples' characteristic vibrational bands are present. The entire temperature range of 0 to 300 K was used to evaluate electrical resistivity both in the absence and in the presence of an applied magnetic field. The increase in bandwidth, which is determined from the Rietveld refinement results, is found to explain why the ρ (T) lowers with increasing Pb concentrations for a given temperature. The calculated magnetoresistance (MR