Expanding the magnetocaloric operation range in Ni–Mn–In Heusler alloys by Cu-doping

We study the magnetocaloric properties of a set of Cu-doped Ni–Mn–In metamagnetic shape memory alloys with the aim of designing composites with large operation range constituted of components of selected Cu-fractions. The studied Cu-doped alloys are characterized by a low hysteresis (~5 K) and by a strong sensitivity of their transition temperatures to an applied magnetic field which ensures excellent reproducibility of the magnetocaloric entropy change ( J K−1 kg−1) upon cyclic application of 6 T. Within the studied composition region, fine-tuning of the Cu-fraction enables shifting the transition temperature by desired amounts. By means of calorimetric measurements under applied magnetic field we show that by assembling samples of tailored compositions it is possible to build a composite showing reversible large magnetocaloric effect (~7.5 J kg−1 K−1) over a broad temperature range of ~30 K.