Magnetic phase transition and magnetocaloric properties of Mn1-xSnxCoGe alloys

Abstract

Magnetic phase transitions and the magnetocaloric effect of the polycrystalline Mn1-xSnxCoGe samples with x=0.02, 0.04, and 0.06 have been investigated. The transformation temperature, room temperature magnetocaloric effect and magnetic orders of these alloys could be effectively tuned by Sn substitution. A detailed study on the critical behavior was performed by various techniques, such as modified Arrott plot, Kouvel–Fisher method, and critical isotherm analysis, to determine the critical exponents (β, γ, and δ). Those exponents calculated from the critical magnetization isotherm were found to obey the Widom scaling relation remarkably well and the validity of the obtained critical exponents was also verified by the prediction of the scaling theory in the critical region. All the results are similar to the theoretical values of the mean-field model, indicating the presence of long-range ferromagnetic coupling in this system. Moreover, we made an attempt to contrast the universal curve for magnetocaloric effect in the present system, finding that rescaled entropy data for all alloys collapse into a universal curve.