Magnetic Phase Transition, Magneto-transport Properties, and Coexistence of Magnetocaloric and Magnetoresitance in (La_0.6Sr_0.4MnO₃)_1−x(CuO)_x Composites

In this study, the magneto-caloric and magneto-transport properties of the perovskites manganites composites (x = 0.00, 0.07, and 0.18) synthesized by the solid-state reaction method are reported. X-ray diffraction (XRD) study to confirm the formation of two phases in composites. The Arrott plot analysis and master curve behavior reveal a second-order magnetic phase transition in the composite samples. Indeed, the value of the magnetic entropy (ΔS_M) correlates with that predicted by Landau and Hamad models. On the other hand, the resistivity of the composite samples was measured at the applied magnetic fields of 0 T, 2 T, and 5 T. All the specimens undergo a metallic–semiconductor transition at the temperature Tρ. The temperature dependence of resistivity shows that the transport behavior is governed by the grain boundaries. It is suggested that the CuO addition acts as a separation layer between grains. Therefore, around room temperature, the magnetoresistance (MR) enhancement of the composite is caused by the magnetic disorder. The enhanced MR and ∆S_M of these composites make them attractive for potential applications.