Abstract
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 similar to 7 K. The measurements of the dependence of AC impedance on temperature allowed to distinguish these magnetic transitions from the nearby martensitic one.