The Overlap of First- and Second-Order Phase Transitions and Related Magnetic Entropy Changes in Ni$_2 + x$Mn$_1 - x$Ga Heusler Alloys

Magnetocaloric effects in Ni–Mn–X based Heusler alloys with X=Ga, Sb, In

“…The interplay between or coupling of the various transitions in Ni 2 Mn(MnX) systems leads to exchange bias effects, giant magnetoresistance, and both inverse and ''normal'' magnetocaloric effects. [ 5,12,[15][16][17]). …”

Magnetocaloric properties of Fe and Ge doped Ni2Mn1−xCuxGa

“…Lately it has gained additional interest due to its possible candidacy as a magnetic refrigerant material. [9][10][11][12][13] Stoichiometric Ni 2 MnGa has an L2 1 crystal structure at room temperature and, upon cooling, it undergoes a first order martensitic structural phase transition ͑at T M = 202 K͒ from the parent cubic ͑austenitic͒ phase to a low temperature ͑LT͒ complex tetragonal structure. The Curie temperature for this is alloy is T C = 376 K. 14 The substitution of Ni for Mn in the Ni 2+x Mn 1−x Ga system results in an increase in T M and decrease of T C and, for 0.17ഛ x ഛ 0.20, the coincidence of T M and T C results in a first order magnetostructural phase transition.…”

Phase transitions and corresponding magnetic entropy changes in Ni2Mn0.75Cu0.25−xCoxGa Heusler alloys

“…Lately it has gained additional interest due to its possible application as a magnetic refrigerant material. 9 In polycrystalline Ni-Mn-Ga, the highest value of ⌬S m = −66.2 J kg −1 K −1 at 350.25 K in a field change of 5 T is observed in Ni 2.19 Mn 0.81 Ga. 13 The coincidence of T M and T C is also reported to be the result of Cu substitution on the Mn sites of Ni 2 MnGa. 14 The Curie temperature of the austenitic phase of this is alloy is T C = 376 K. 14 The substitution of Ni for Mn in the Ni 2+x Mn 1−x Ga system results in an increase in T M and a decrease of T C and, for 0.17Յ x Յ 0.20, the coincidence of T M and T C results in an apparent first order magnetostructural phase transition.…”

“…[9][10][11][12][13] Stoichiometric Ni 2 MnGa has an L2 1 crystal structure at room temperature and, upon cooling, it undergoes a first order martensitic structural phase transition ͑at T M Ϸ 220 K͒ from the parent cubic ͑austenitic͒ phase to a low temperature ͑LT͒ complex tetragonal structure. Lately it has gained additional interest due to its possible application as a magnetic refrigerant material.…”