Magnetic and Magnetocaloric Properties of SrRu11xFexO3

We have systematically investigated the crystalline and electronic structures, magnetic and magnetocaloric properties of polycrystalline SrRu1_xFexO3 (x = 0 and 0.1) samples fabricated by the solid-state reaction method. The X-ray diffraction analyses of the samples indicated single phase orthorhombic perovskite structure. A thorough analysis of X-ray-absorption-based electronic structure revealed that both Fe2+ and Fe3+ ions are present in x = 0.1, in which concentration of Fe3+ ions is higher than that of Fe2+ ions. More careful analyses on the isothermal magnetization data derived from the Banerjee's criterion demonstrated that the ferromagnetic-paramagnetic phase transition in all samples belongs to the second-order phase transition type. These results were also confirmed by a recently proposed quantitative criterion, which considered an exponent n from the magnetic field and temperature dependences of the magnetic entropy change (ASm). Especially, around TC, we have found that the ASm reaches the maximum values of 1.65 and 1.32 J.kg_1.K_1 for x = 0 and 0.1, respectively, for a field change of AH= 50 kOe. Magnetic -field dependences of the maximum magnetic-entropy change (ASmax) obey a power law of ASmax(H) pound Hn, where the values of n = 0.92-0.94 are far from the mean -field-theory value (2/3), indicating short-range magnetic order existing in the samples