Electrical and magnetic properties of La0.7Ca0.3Mn0.9Co0.1O3 locating at a threshold of the first- and second-order phase transitions

Abstract In this work, a polycrystalline sample of La0.7Ca0.3Mn0.9Co0.1O3 was prepared by solid-state reaction method. The room-temperature X-ray diffraction analysis using Rietveld refinement technique confirms that the sample has a single-phase state with the orthorhombic structure (space group Pbnm). Based on the temperature dependences of the resistance and magnetization, the magnetoresistance and the magnetocaloric effects of the sample have been investigated. Our results pointed out that La0.7Ca0.3Mn0.9Co0.1O3 compound exhibits the maximum magnetoresistance MR = 100% × [ρ(0) − ρ(H)]/ρ(H) = 14.3% near the metal–semiconductor transition with TP = 155 K and the maximum magnetic entropy change |ΔSmax| = 1.45 J/kg·K around the ferromagnetic–paramagnetic phase transition with TC = 188 K under an applied magnetic field change ΔH = 4 kOe. Besides, the changes of the specific heat ΔCP(T, H) for ΔH = 1–4 kOe have been also calculated.