Correlation between Critical Behavior and Magnetocaloric Effect near Paramagnetic to Ferromagnetic Phase Transition of Co2TiAl0.75Si0.25Heusler Alloy

Heusler alloys have drawn considerable interest, due to their tunable properties, for technological applications. The literature review reveals that the critical exponents and magnetocaloric effect (MCE) of Co(2)TiAl(0.75)Si(0.25)quaternary Heusler alloy need to be established. Hence, Co(2)TiAl(0.75)Si(0.25)alloy is prepared by the arc melting method. Critical exponents of the alloy are obtained by analyzing magnetic isotherms with various techniques, such as Arrot plots, Kouvel-Fisher plots, critical isotherm analysis, and magnetocaloric analysis near the transition temperature. The paramagnetic to ferromagnetic transition temperature is found to be approximate to 235 +/- 2.5 K. The nature of the Arrot plots and the universal curve of the MCE confirm this as a second-order phase transition. Despite the moderate magnetocaloric values, the large working temperature (approximate to 75 K at 3 T) makes this alloy a potential candidate for a multistage magnetic refrigeration application. The critical exponents obtained from different techniques fall in between the theoretical prediction from the mean field theory, which indicates long-range ferromagnetic exchange interaction, and the 3D Heisenberg model, implying short-range interaction. The range of interaction (sigma = 1.727) also confirms this. This complex magnetic interaction may arise from the competition between localized and itinerant electron present in the system.