Effect of pressure on the magnetocaloric properties of nickel-rich Ni–Mn–Ga Heusler alloys

Abstract

Nickel-rich Ni–Mn–Ga Heusler alloys were prepared by arc melting and subsequent homogenization by annealing. A large magnetic entropy change was observed around 291 K in the alloy where martensite-austenite structural and ferro-para magnetic transitions almost coincide with each other. The effect of hydrostatic pressure of up to 8 kbar on magneto-structural transitions, magnetocaloric effect, and magnetic hysteresis was studied. The martensitic transition temperature as well as the Curie temperature TC was found to increase, whereas the magnetic entropy change |ΔSM| decreases slightly due to the application of hydrostatic pressure. The large hysteresis observed in M versus H curve at the ambient pressure almost vanishes due to the application of 8 kbar pressure.