Thermal hysteresis evaluation of the MnAs compound near room temperature

This work employs a thermal analysis experimental procedure that contributes for understanding of the MnAs compound thermal hysteresis associated with its magnetic transition near room temperature. The study was performed using a differential scanning calorimeter and different heating rates in a temperature interval around the magnetic transition temperature. The experiment consisted in two procedures, the first one analyzed the onset and peak temperatures of the thermal event associated with the magnetic transition at different heating rates. The second procedure consisted in the analysis of the formation and decomposition of the phase associated with the magnetic transition by means of the thermal event enthalpy as a function of the temperature. The results show that the onset temperatures during cooling increase almost linearly with cooling rate and the onset temperatures during heating are almost constant. Also, the transition enthalpy changes with heating rate and with reaction progress, exhibiting different behaviors during heating and cooling, thus suggesting two different mechanisms for the phase transition.