Magneto-structural transition and magnetocaloric effect of Ni_50-xTb_xMn₃₀Ga₂₀ (x = 0−1) alloys

The magneto-structural transition, magnetic properties and magnetocaloric effect of the Ni_50-xTb_xMn₃₀Ga₂₀ (x = 0−1) alloys were studied. It was found that both the martensitic and magnetic transition temperatures were insensitive to the addition of Tb element. For the alloys with x = 0 and x = 1, the martensitic transformation and magnetic transition take place independently. For the alloys in the range of 0.1 ≤ x ≤ 0.8, coincidence of martensitic and magnetic transitions was detected, which resulted in a magneto-structural coupling transition from ferromagnetic martensite to paramagnetic austenite. The saturation magnetization of the martensite phase at 300 K marginally decreased with the addition of Tb element. Considerable and stable magnetic entropy change of approximate 6 JK⁻¹ Kg⁻¹ was obtained in vicinity of the magneto-structural transitions in the dual-phase alloys with 0.1 ≤ x ≤ 0.8.