Giant entropy change at the co-occurrence of structural and magnetic transitions in the Ni $ \mathsf {_{2.19}}$ Mn $ \mathsf {_{0.81}}$ Ga Heusler alloy

Abstract

We have studied the isothermal entropy change around a first-order structural

Phase diagram and magnetocaloric effect ofCoMnGe1-xSnxalloys

“…In the case of the magnetostructual transitions presented here, thermal hysteresis is around 20 K, and we would expect field hysteresis to be similarly significant. We can estimate the field hysteresis from the rate of shift of the transition temperature with applied field (of the order of 1 K/Tesla, similar to that in Ni-Mn-Ga shape memory martensitic alloys [7]). Then a thermal hysteresis of 20 K corresponds to a field hysteresis of 20 Tesla.…”

“…In such cases, hysteresis can be minimal. In the case of magnetostructural transitions, a different crystal structure is found on either side of the phase transition, for example in Gd 5 (Si 1−x Ge x ) 4 [1] or in shape memory alloys such as Ni 2+x Mn 1−x Ga [7]. In these cases, hysteresis can be much larger and there have been efforts, via controlled doping, to minimise it [8].…”

Large magnetocaloric effects in magnetic intermetallics: First-principles and Monte Carlo studies

“…Magnetic superelasticity is involved in the stabilization of the phase with highest magnetization in an external magnetic field [5,6]. In addition to shape memory and superelasticity, these alloys (ternary magnetic shape memory Heusler alloys of type Ni-(Co)-Mn-(Cr)-(Al, Ga, In, Sn, Sb)) exhibit magnetocaloric (conventional and inverse) [7,8,9], barocaloric [10] and elastocaloric [11] effects, magnetoresistance [12], exchange bias [13] and kinetic arrest [14]. Also spin-glass [15] and strain-glass [16] features have been reported on several of these Heusler alloys.…”

Magnetocaloric and magnetic properties of Ni2Mn1−xCuxGa Heusler alloys: An insight from the direct measurements and ab initio and Monte Carlo calculations

“…14 In a concentration interval 0:18 x 0:27 the structural and the magnetic phase transition merge, i.e., these alloys undergo a coupled first order magnetostructural phase transition from ferromagnetic martensite to paramagnetic austenite. Judging by the reported value of isothermal magnetic entropy change, 15 giant MCE materials though their adiabatic temperature change measured experimentally by a direct method 16,17 turned our to be comparable with that of Gd.…”