The effect of temperature span of the first-order transition processes on magnetic entropy change in NiMnGa alloys

The effects of temperature span of the first-order phase transition on the entropy change are investigated experimentally in NiMnGa alloys. The correlation between the transition temperature span from the ferromagnetic martensite to paramagnetic austenite and the magnetic entropy change is found. A wider transition temperature span leads to “table”-like ΔS peak and a narrow one leads to “λ”-like ΔS peak in NiMnGa alloys with the magnetic phase transition in the vicinity of the structural phase transition. The structure phase transition process also affects the relative cooling power.