Effect of partial substitution of Ni by Co on the magnetic and magnetocaloric properties of Ni50Mn35In15 Heusler alloy

The magnetic and magnetocaloric properties of Ni48Co2Mn35In15 were studied using magnetization and heat capacity measurements. The magnetic entropy change (Delta S-M) was evaluated from both magnetizing and demagnetizing fields. An inverse Delta S-M for the magnetizing and demagnetizing processes were found to be 20.5 and 18.5 J kg(-1) K-1, respectively, for Delta H = 5 T at the martensitic transition (T = T-M). The normal Delta S-M was found to be -5.4 J kg(-1) K-1 for both fields at the paramagnetic/ferromagnetic transition (T = T-C). 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. (C) 2011 American Institute of Physics. [doi:10.1063/1.3540696]