Adiabatic Temperature Change in Metamagnetic Ni(Co)-Mn-AI Heusler Alloys

摘要

Two representatives of Ni(Co)-Mn-Al metamagnetic shape memory alloy system, Ni_(45)Co_5Mn_(31)Al_(19) and Ni_(35)Co_(15)Mn_(35)Al_(15), have been studied with respect to their magnetocaloric properties. Experimental study of the magnetocaloric effect by a direct measurement of the adiabatic temperature change ΔT_(ad) revealed that in both the samples ΔT_(ad) depends on the measurement protocol as well as on the magnetic prehistory of the samples. For the applied magnetic field μ_0H = 1.93 T, the largest adiabatic temperature change, |ΔT_(ad)| ≈ 0.7 K, has been observed in the Ni_(35)Co_(15)Mn_(35)Al_(15) sample at T= 464 K.