Europium substitution effects on structural, magnetic and magnetocaloric properties in La_0.5Ca_0.5MnO₃

¹ Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, B. P. 1171, 3000 Sfax, Tunisie
² Institut NEEL, CNRS, B.P.166, 38042 Grenoble Cedex 9, France

^a e-mail: akramkri@hotmail.fr

Abstract

We have investigated structural, magnetic and magnetocaloric properties of polycrystalline samples La_0.5-xEu_xCa_0.5MnO₃ (x=0 and 0.1). Rietveld refinement of the X-ray diffraction patterns show that our samples are single phase and crystallize in the orthorhombic structure with Pnma space group. Magnetization measurements versus temperature at a magnetic applied field of 500 Oe indicate that La_0.4Eu_0.1Ca_0.5MnO₃ sample exhibits a paramagnetic to ferromagnetic transition with decreasing temperature. Magnetic measurements reveal strong magnetocaloric effect in the vicinity of the Curie temperature T_C. The parent compound shows a negative magnetic entropy change of ∆S_M=−1.13Jkg⁻¹K⁻¹ at 220K and a positive magnetocaloric effects ∆S_M=1Jkg⁻¹K⁻¹ at 150K under a magnetic applied field of 2T. La_0.4Eu_0.1Ca_0.5MnO₃ exhibits a maximum value of magnetic entropy change ∆S_M=−1.15Jkg⁻¹K⁻¹ at 130K under an applied field of 2T and a large relative cooling power RCP with a maximum value of 72 J/kg.