On the Magnetotransport Properties and Griffith Phase in the \(({\varvec{L}}{\varvec{a}},{{\varvec{G}}{\varvec{d}})}_{1.4}({{\varvec{C}}{\varvec{a}},{\varvec{S}}{\varvec{r}})}_{1.6}{\mathbf{M}\mathbf{n}}_{2}{\mathbf{O}}_{7}\) Double-Layered Manganites

Abstract

The double-layered manganite \({La}_{1.2}{Gd}_{0.2}{Ca}_{1.2}{Sr}_{0.4}{Mn}_{2}{O}_{7}\) was prepared by the solid-state reaction route, and its structural, microstructural, magnetic, electrical, and magnetotransport properties were investigated. Rietveld refinement analysis of the X-ray diffractogram shows that the structure is indexed in a tetragonal structure with an I4/mmm space group with an impurity phase. The microstructure was examined using scanning electron microscopy. The purity of the sample was examined by the energy-dispersive X-ray spectroscopy investigation. In the context of magnetic measurements, inverse susceptibility, hysteresis loop, and the magnetic behavior of the compound are discussed in detail. The sample displays a phase transition from ferromagnetic (FM) to paramagnetic (PM) at \({T}_{C}\), which is equal to 290.13 K. Additionally a Griffith phase (GP) was identified and was found to be 339 K. The sample can be thought of as spin-glass-like since a significant divergence was observed at low temperatures between the magnetization curves M (T) in the zero-field cooling (ZFC) and in the field cooling (FC) modes. The electrical resistivity under an applied magnetic field of 1 T exhibits a metal–insulator transition (\({T}_{MI}\)) at 152.98 K. The magnetoresistance was observed to decrease with increasing temperature, peaking at 23% at 11 K. The electrical resistivity in the ferromagnetic region (\(T < T_{MI}\)) has been found to be a combination of residual resistivity and resistivities due to the weak localization, and to the electron–electron, while the adiabatic small polaron and variable range hopping models may be used to explain the resistivity data at high temperature in paramagnetic region (\(T> T_{MI}\)).