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 Co₂TiAl_0.75Si_0.25 quaternary Heusler alloy need to be established. Hence, Co₂TiAl_0.75Si_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 ≈235 $\pm$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 (≈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 (σ = 1.727) also confirms this. This complex magnetic interaction may arise from the competition between localized and itinerant electron present in the system.

中文翻译：

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Co2TiAl0.75Si0.25 Heusler合金的顺磁至铁磁相变附近的临界行为与磁热效应的相关性

霍斯勒合金由于其可调性而引起了人们的广泛兴趣，用于技术应用。文献综述表明，需要建立Co ₂ TiAl _0.75 Si _0.25四元Heusler合金的临界指数和磁热效应（MCE）。因此，通过电弧熔化法制备了Co ₂ TiAl _0.75 Si _0.25合金。通过使用各种技术分析磁等温线，例如在过渡温度附近的Arrot图，Kouvel-Fisher图，临界等温线分析和磁热分析，可以获得合金的临界指数。发现顺磁性到铁磁性的转变温度约为235$\pm$2.5 K. Arrot图的性质和MCE的通用曲线将其确认为二阶相变。尽管磁热值适中，但较大的工作温度（3 T时约为75 K）使该合金成为多级磁制冷应用的潜在候选者。通过不同技术获得的临界指数介于平均磁场理论（表示长距离铁磁交换相互作用）的理论预测与3D Heisenberg模型（暗示短距离相互作用）之间。相互作用范围（σ=  1.727）也证实了这一点。这种复杂的磁相互作用可能是由于系统中存在的局部电子和迭代电子之间的竞争而引起的。