Universal curve for adiabatic temperature change in Ni$_{45.37}$Mn$_{40.91}$In$_{13.72}$ Heusler alloy under AC magnetic fields

Direct measurements of the adiabatic temperature change $\Delta T_{\rm ad}$ depending on the temperature and frequency of magnetic field changes in the Ni$_{45.37}$Mn$_{40.91}$In$_{13.72}$ 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.