Magnetotransport properties and magnetocaloric effects of Mn_1.95Cr_0.05Sb_0.95Ga_0.05 compound

The magnetotransport properties and magnetocaloric effects of the compound Mn_1.95Cr_0.05Sb_0.95Ga_0.05 have been studied. With decreasing temperature, a spontaneous first-order magnetic phase transition from ferrimagnetic (FI) to antiferromagnetic (AF) state takes place at T_\rm s=200K. A metamagnetic transition from the AF to FI state can be induced by an external field, accompanied by a giant magnetoresistance effect of 57%. The magnetic entropy changes are determined from the temperature and field dependence of the magnetization using the thermodynamic Maxwell relation. Mn_1.95Cr_0.05Sb_0.95Ga_0.05 exhibits a negative magnetocaloric effect, and the absolute values of \Delta S_\rm M^\rm max(T, \Delta H) are 4.4, 4.1, 3.6, 2.8 and 1.5 J/(kg\cdotK) for magnetic field changes of 0－5T, 0－4T, 0－3T, 0－2T and 0－1T, respectively.