Investigation of Magnetic and Magnetocaloric Properties in disordered Spinel Compound Fe2−xCuxSnS4

Abstract

Chalcogenides have attracted considerable attention not only due to prospective applications in in thermoelectric, superconductivity, magnetocaloric but also because of the diverse structural properties. Iron and copper-based ternary metal chalcogenides offer an extra dimension in terms of magnetism and magnetocaloric application, that makes them more intriguing. From earlier study in our group, it was observed that the magnetic properties in Mn2SnS4 can be tuned by suitable substitution at different sites. To further understand the magnetic properties and the effect of substitution in the Fe-analogue, Fe2SnS4, we have studied the effect of Cu substitution on the structure and magnetic properties in Fe2-xCuxSnS4. [1] In this work we repot a detailed electronic, magnetic, structural, and thermodynamic investigation on Fe2-xCuxSnS4 using both experimental and theoretical Study. From magnetic measurements, we have observed one distinct magnetic transition at 230 K, associated with ferrimagnetic ordering which can be rationalized by taking into account the changes in the distribution of magnetic centres within the structure arising from the Cu substitution at Fe site. XPS study indicates that Fe exists in both +2 and +3 oxidation states while Cu, Sn and S adopt +1, +4 and −2 oxidation states, respectively. Magnetic susceptibility study suggests ferrimagnetic like ordering in Fe1.6Cu0.4SnS4 below 230 K and the ordering temperature gradually decreases from 230 K to about 120 K with increase in Cu substitution. As the amount of Cu(I) increases in Fe2−xCuxSnS4, the percentage of Fe(III) increases to balance the charge. The magnetocaloric properties of polycrystalline Fe1.6Cu0.4SnS4 has been studied for their potential applications as magnetic refrigerant at cryogenic temperatures. With an applied magnetic field of five Tesla, the maximum value of magnetic entropy change was found to be (Δ Sm) 0.4 Jkg−1K −1 with a relative cooling power (RCP) of 7 J kg−1 . These values are very similar to the literature reported values for Cu and Fe based compounds. Further, manipulation at the Fe site may lead to enhancement of magnetocaloric effect for practical applications.