Structural, Magnetic and Magnetotransport Properties of La0.7Ca0.18Ba0.12Mn0.95Sn0.05O3 Perovskite Manganite

Abstract

This paper reports a study on the structural, magnetic and magnetotransport properties of the mixed-valence perovskite manganite La_0.7Ca_0.18Ba_0.12Mn_0.95Sn_0.05O₃ (LCBMSO), synthesized by a solid-state reaction method. The results of X-ray powder diffraction analysis confirm that the sample possesses a single orthorhombic phase with space group Pnma. The Rietveld refinement results reveals that LCBMSO contains distorted MnO₆ octahedron. Micrographs obtained by scanning electron microscopy showed that the sample grains have a polygonal shape and are in the micrometer size range. Fourier transform infrared spectroscopy analysis confirms the presence of Mn–O–Mn and Mn–O stretching vibration. The magnetization–temperature curve displays a paramagnetic–ferromagnetic transition at T_C = 145 K. A slight bifurcation between the zero-field curve and the cooling-field curve was noticed, which is attributed to spin-glass behavior. Based on the hysteresis cycle, a soft ferromagnetic behavior was observed in our sample at temperatures of 1.8 and 100 K. The electrical resistivity vs temperature curve shows a metal–insulator transition at T_MI = 154 K. The magnetoresistance ratio reached 30% at an applied magnetic field of 1 T, making the LCBMSO material an attractive candidate for use as a magnetoresistive sensor in various industrial applications. The temperature coefficient of resistivity reached 3.35%, making this material suitable for use in infrared and bolometric detectors. The relation ρ = ρ₀ - ρ_0.5 T^0.5 + ρ₂ T² + ρ₅ T⁵ was employed to fit the low-temperature resistivity data below T_MI, whereas the variable range hopping and small polaron hopping models were used to fit the data in the insulating region above T_MI.