Giant field-induced adiabatic temperature changes in Ni-Mn-In-based Heusler alloys

Direct measurements of the adiabatic temperature change ($\Delta $T$_{\mathrm{AD}})$ of Ni$_{\mathrm{50}}$Mn$_{\mathrm{35}}$In$_{\mathrm{14.5}}$B$_{\mathrm{0.5\thinspace }}$have been done using an adiabatic magnetocalorimeter in a temperature range of 250-350 K, and with magnetic field changes up to $\Delta $H$=$1.8 T. The initial susceptibility in the low magnetic field region drastically increases with temperature starting at about 300 K. Magnetocaloric effects (MCE) parameters were found to be a linear function of H$^{\mathrm{2/3\thinspace }}$in the vicinity of the second order transitions (SOT), whereas the first order transitions (FOT) do not obey the H$^{\mathrm{2/3\thinspace }}$law due to the discontinuity of the transition. The relative cooling power (RCP) based on the adiabatic temperature change for a magnetic field change of 1.8 T has been estimated. Maximum values of $\Delta $T$_{\mathrm{AD}} \quad =$ -2.6 K and 1.7 K were observed at FOT and SOT for $\Delta $H$=$1.8 T, respectively. Acknowledgement This work was supported by the Office of Basic Energy Sciences, Material Science Division of the U.S. Department of Energy, DOE Grant No. DE-FG02-06ER46291 (SIU) and DE-FG02-13ER46946 (LSU).