Universal Curve for Adiabatic Temperature Change in Ni45.37mn40.91in13.72 Heusler Alloy Under Ac Magnetic Fields

Direct measurements of the adiabatic temperature change ∆ T ad depending on the temperature and frequency of magnetic field changes in the Ni45.37Mn40.91In13.72 Heusler alloy were carried out. The dependence of the magnetocaloric effect (MCE) on frequency in this alloy is anomalous: the MCE decreases with frequency more strongly in the region of the magnetic phase transition than in the region of the magnetostructural phase transition. A universal curve of adiabatic temperature change in magnetic fields of different frequencies is proposed, which shows that there is a deviation from the universal behavior at frequencies of 30 Hz, which can be explained by the thermal inertia of the thermocouple. Using such a phenomenological universal curve, experimental results can be extrapolated to magnetic field frequencies that are inaccessible in the laboratory or frequencies at which it is impossible to measure using known techniques.