Effects of copper substitution to Mn-site on magnetic and magnetocaloric properties of La0.7Sr0.3Mn1-xCuxO3 manganites

Abstract

In present study, the effects of copper substitution on the magnetic and magnetocaloric properties of La0.7Sr0.3Mn1-xCuxO3 manganite samples were investigated. La0.7Sr0.3Mn1-xCuxO3 samples were obtained by using sol-gel method. X-ray diffraction analyses were performed to determine structural properties such as lattice parameters and crystal structure. The crystal structure of the samples is rhombohedral with space group R3 ̅c. The Cu substitution to the Mn-site causes a decrease in the magnetic phase transition temperature (TC) of the samples. By using Banerjee criterion and Landau theory, the type of magnetic phase transition is determined as second order. From isothermal magnetization measurements, magnetic entropy change (-∆S_M) values were calculated for different magnetic field changes of the samples. The maximum magnetic entropy change value (-∆S_M^max) determined from the temperature dependence of -∆S_M curves for the samples is 3.39 and 2.78 JKg-1K-1 under 5 T, respectively. Relative cooling power (RCP) values of the samples were found as 249.52 and 111.98 Jkg-1 for 5 T, respectively.