The effect of the substitution of Cu for Mn on magnetic and magnetocaloric properties of Ni50Mn34In16

The influence of Cu substitution for Mn on magnetic and magnetocaloric properties has been investigated in Ni50Mn34−xCuxIn16 (x=1.3 and 1.6) Heusler alloys by using calorimetric and magnetic measurements. The temperature dependent magnetization measurements and calorimetric studies indicate that martensitic transition temperatures shift to higher temperatures with increasing valence electron concentrations, e/a. The isothermal magnetization curves around the martensitic transition temperatures show a typical metamagnetic behavior. Associated with that, large positive values of magnetic entropy changes around structural transition region were determined by using the Maxwell and Clausius-Clapeyron relations. The maximum magnetic entropy change values were found to be 25.2 and 5.7 J kg−1 K−1 for Ni50Mn34−xCuxIn16 (x=1.3 and 1.6) alloys by Maxwell relation in a magnetic field change of 2 T. In order to understand the limit can be reached for, the magnetic entropy change values recalculated by Clausius-Clapeyron relation. Obtained maximum entropy change values are 22.8 and 16.3 J kg−1 K−1 for Ni50Mn34−xCuxIn16 (x=1.3 and 1.6) alloys by Clausius-Clapeyron relation.