Structural, magnetic and theoretical investigations on the magnetocaloric properties of La0.7Sr0.25K0.05MnO3 perovskite

Abstract

The La_0.7Sr_0.25K_0.05MnO₃ (LSKMO_0.05) manganite compound was synthesized by the solid state reaction method. X-ray diffraction analysis revealed that this sample crystallizes in the distorted rhombohedral system with the Rc space group. The magnetic study showed a second order paramagnetic (PM)-ferromagnetic (FM) transition at the Curie temperature T_C = 332 K. In addition, isothermal measurements of magnetization allowed us, through thermodynamic Maxwell relations, to determine the magnetic entropy change (ΔS_M). The maximum magnetic entropy change (ΔS_max) and the relative cooling power (RCP) were found to be, respectively, 2.37 J kg⁻¹ K⁻¹ and 102 J kg⁻¹ for a 2 T magnetic field change along with a negligible hysteresis loss, making this material a promising candidate for magnetic refrigeration. In order to eliminate the drawbacks due to the use of multistep nonlinear fitting in a conventional manner, the field dependence of magnetic entropy change was applied to study the critical behavior. As expected, our results are consistent with the values derived for the 3D-Heisenberg model.