Structural, electrical transport and magnetoresistance properties of La0.7Ca0.3MnO3:ZnO nanocomposites

Abstract In the present communication, (1–x) La0.7Ca0.3MnO3 (LCMO) + (x) ZnO (x = 0, 0.10, 0.20) nanocomposites were synthesized by sol–gel method and studied for their charge carrier transport properties. The result of X–ray diffraction (XRD) confirms mixed phases of orthorhombic LCMO with hexagonal ZnO. ZnO admixing does not show any significant change in lattice parameters of LCMO however the peak intensity and crystallinity get suppressed with increase in ZnO content. The samples have been characterized for their electrical transport behaviors using four probe resistivity measurements which confirm that all the studied samples exhibit characteristic insulator to metal transition at temperature TP that decreases with increase in ZnO content. There is a discrepancy in the resistivity values between the LCMO: ZnO nanocomposite samples having the ZnO contents x = 0.10 and 0.20. Variations in the charge carrier transport parameters (i.e. resistivity and TP) with ZnO content have been attributed to the magnetic interactions between manganite and ZnO phases and phase separation scenario in LCMO manganite phase. Various models and mechanisms have been employed to understand the charge conduction processes across the lattices of studied nanocomposites. The largest magnetoresistance (MR) has been seen for x = 0.20 in the LCMO: ZnO nanocomposite which has been attributed to the different distribution possibilities of ZnO within the LCMO manganite lattice of the nanocomposite samples.