Effect of partial substitution of Ni by Co on the magnetic and magnetocaloric properties of Ni_(50)Mn_(35)In_(15) Heusler alloy

摘要

The magnetic and magnetocaloric properties of Ni_(48)Co_2Mn_(35)In_(15) were studied using magnetization and heat capacity measurements. The magnetic entropy change (△S_m) was evaluated from both magnetizing and demagnetizing fields. An inverse △S_m for the magnetizing and demagnetizing processes were found to be 20.5 and 18.5 J kg"1 K"1, respectively, for △H= 5 T at the martensitic transition (T=T_M). The normal △S_M was found to be-5.4 J kg~(-1) K~(-1) for both fields at the paramagnetic/ferromagnetic transition (T=Tc). The effective refrigeration capacity at T_M and T_c for magnetizing field was found to be 268 and 243 J/kg (285 and 243 J/kg for the demagnetizing field), respectively. We have also estimated the density of states, the Debye temperature, and the inverse adiabatic temperature change to be 4.93 states/eV f.u., 314 K, and-3.7 K, respectively, from the measured heat capacity data.