Giant magnetocaloric effect in isostructural MnNiGe-CoNiGe system by establishing a Curie-temperature window

Abstract

An effective scheme of isostructural alloying was applied to establish a Curie-temperature window in isostructural MnNiGe-CoNiGe system. With the simultaneous accomplishment of decreasing structural-transition temperature and converting antiferromagnetic martensite to ferromagnetic state, a 200 K Curie-temperature window was established between Curie temperatures of austenite and martensite phases. In the window, a first-order magnetostructural transition between paramagnetic austenite and ferromagnetic martensite occurs with a sharp jump in magnetization, showing a magnetic entropy change as large as -40 J kg -1 K -1 in a 50 kOe field change. This giant magnetocaloric effect enables Mn 1-x Co x NiGe to become a potential magnetic refrigerant.

The magneto-structural transition in Mn1−xFexCoGe

“…These RC values are larger than the values of 184 J kg -1 obtained for MnCoGe0.95Ga0.05 [48] or 159 J kg -1 for Mn0.9Ni0.1CoGe [49], and comparable with 240 J kg -1 for Mn0.9Fe0.1CoGe [33] (with a field change of 5 T). Isothermal magnetic entropy changes -∆SM as a function of temperature for Mn0.98Fe0.02CoGe…”

Structural and magnetic properties of MnCo 1−x Fe x Si alloys

“…In recent years, the magnetic hexagonal MM'X (M, M' = transition metals, X = carbon or boron group elements) alloys [1] have drawn increasing attention due to their remarkable magnetoresponsive properties, such as magnetic-field-induced martensitic transformation [2][3][4][5], giant magnetocaloric effect [3,4,[6][7][8][9], magnetoresistance [10] and magneto-strain [11,12]. It is therefore of interest for the smart applications and explorations of new functional materials.…”

Wide temperature window of magnetostructural transition achieved in Mn0.4Fe0.6NiSi1−xGax by a two-step isostructural alloying process

“…[18][19][20][21] In particular, the coupling of magnetic and structural transitions, which often results in large MCE, can be accomplished by isostructural alloying. This method was first proposed by Liu et al in the MnNi 1−x Fe x Ge system, which has built a large "temperature window" for the magnetostructural transition.…”