Magnetocaloric effect in Ni2(Mn,Cu)Ga0.84Al0.16 Heusler alloys

Abstract 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 heat capacity measurements, both as a function of temperature and magnetic field. The compound Ni2Mn0.75Cu0.25Ga0.84Al0.16 presents a large magnetocaloric effect at a transition between magnetically aligned structures. In addition, Ni2Mn0.70Cu0.30Ga0.84Al0.16 shows very high entropy change at room temperature, although irreversible, under a magnetic field change 0 - 1 T. The magnetocaloric properties of the studied samples are compared with selected compounds in the literature.