Room temperature magnetocaloric effect, critical behavior, and magnetoresistance in Na-deficient manganite La0.8Na0.1MnO3

• Published in: Journal of applied physics 2014-05, Vol.115 (19)
• Main Authors: Khlifi, M., Dhahri, E., Hlil, E. K.
• Format: Article
• Language: English
• Subjects: Crystallization; Curie temperature; Electrical resistivity; Entropy; Ferromagnetism; Magnetic fields; Magnetism; Magnetoresistance; Magnetoresistivity; Mean field theory; Metal-insulator transition; Phase transitions; Physics; Room temperature; Temperature dependence; X-ray diffraction
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.4879098

The La0.8Na0.1MnO3 oxide was prepared by the solid-state reaction and annealed in air. The X-ray diffraction data reveal that the sample is crystallized in a rhombohedral structure with R3¯c space group. Magnetic study shows a second-order magnetic phase transition from ferromagnetic to paramagnetic state at the Curie temperature TC = 295 K. In addition, the magnetizations as a function of temperature and the magnetic field is used to evaluate the magnetic entropy change ΔSM. Then, we have deduced that the La0.8Na0.1MnO3 oxide has a large magnetocaloric effect at room temperature. Such effect is given by the maximum of the magnetic entropy change ΔSMmax = 5.56, and by the Relative cooling power (RCP) factor which is equal to 235 under a magnetic field of 5 T. Moreover, the magnetic field dependence of the magnetic entropy change is used to determine the critical exponents β, γ, and δ which are found to be β = 0.495, γ = 1.083, and δ = 3.18. These values are consistent with the prediction of the mean field theory (β = 0.5, γ = 1, and δ = 3). Above all, the temperature dependence of electrical resistivity shows a metal–insulator transition at Tρ. The electrical resistivity decrease when we apply a magnetic field giving a magnetoresistance effect in the order of 60% at room temperature.