  Polycrystalline Heusler compounds Ni2Mn0.75Cu0.25Ga0.84Al0.16 with a
martensitic transition between ferromagnetic phases and
Ni2Mn0.70Cu0.30Ga0.84Al0.16 with a magnetostructural transformation were
investigated by magnetization and thermal measurements, both as a function of
temperature and magnetic field. The compound Ni2Mn0.75Cu0.25Ga0.84Al0.16
presents a large magnetocaloric effect among magnetically aligned structures
and its causes are explored. In addition, Ni2Mn0.70Cu0.30Ga0.84Al0.16 shows
very high, although irreversible, entropy and adiabatic temperature change at
room temperature under a magnetic field change 0-1 T. Improved refrigerant
capacity is also a highlight of the 30% Cu material when compared to similar
Ni2MnGa-based alloys.
