The existence of two Curie temperatures in the temperature interval of the martensitic phase of a Ni51.9Mn27.0Ga21.1 alloy has been verified. This phenomenon was confirmed in both magnetic and electrical impedance measurements. Additionally, modified Arrott plot calculations were employed to determine order and temperatures of magnetic transitions occurring in a Ni51.9Mn27.0Ga21.1 alloy. The results of the calculations are in line with the ones obtained in the experiments. They indicate that the second-order transitions on cooling and heating in this alloy occur at different temperatures with thermal hysteresis of ~7 K. The measurements of the dependence of AC impedance on temperature allowed to distinguish these magnetic transitions from the nearby martensitic one.

中文翻译：

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Ni51.9Mn27.0Ga21.1合金中磁转变的顺序和温度

验证了Ni51.9Mn27.0Ga21.1合金马氏体相温度区间存在两个居里温度。这种现象在磁阻抗和电阻抗测量中都得到了证实。此外，采用改进的阿罗特图计算来确定 Ni51.9Mn27.0Ga21.1 合金中发生的磁转变的顺序和温度。计算结果与实验得到的结果一致。他们表明，这种合金在冷却和加热时的二阶转变发生在不同温度下，热滞约为 7 K。交流阻抗对温度的依赖性的测量允许将这些磁转变与附近的马氏体转变区分开来。