Evidence of Change in the Density of States during the Martensitic Phase Transformation of Ni-Mn-In Metamagnetic Shape Memory Alloys

Abstract

Specific heat measurements were performed at low temperatures for Ni 50 Mn 50−x In x alloys to determine their Debye temperatures (θ D ) and electronic specific heat coefficients (γ). For x ≤ 15, where the ground state is the martensite (M) phase, θ D decreases linearly and γ increases slightly with increasing In content. For x ≥ 16.2, where the ground state is the ferromagnetic parent (P) phase, γ increases with decreasing In content. Extrapolations of the composition dependences of θ D and γ in both the phases suggest that these values change discontinuously during the martensitic phase transformation. The value of θ D in the M phase is larger than that in the P phase. The behavior is in accordance with the fact that the volume of the M phase is more compressive than that of the P phase. On the other hand, γ is slightly larger in the P phase, in good agreement with the reported density of states around the Fermi energy obtained by the first-principle calculations.

Novel Research for Development of Shape Memory Alloys

“…Further theoretical investigation of the phase diagram for Ni 2 MnGa 1-x Fe x is needed. Umetsu et al performed the specific heat measurements at low temperatures for Ni 50 Mn 50−x In x alloys to determine their Debye temperatures θ D and electronic specific heat coefficients γ, and investigated the change in the density of states during the martensitic phase transformation[34]. The γ was slightly larger in the parent phase, in good agreement with the reported density of states around the Fermi energy obtained by the first-principle calculations.…”

Disorder-mediated quenching of magnetization in NbVTiAl: Theory and experiment

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<i>In-Situ</i> Study of Phase Transformation and Microstructural Evolution of Ni₄₅Mn₃₇In₁₃Co₅ Metamagnetic Shape Memory Alloy

“…Correspondingly, MSMA has been the research hotspot in the fields of condensed matter physics and materials science. 17) Among the reported MSMA systems, the NiMn based Heusler shape-memory alloys exhibit the magnetic-field-induced strain effect, 810) the magnetic-field-induced reverse martensitic transformation, 11) the giant magneto-resistance effect 12,13) and the (inverse) magnetocaloric effect 1418) in the vicinity of the martensitic transformation temperature. Such features make it a good candidate for future applications in the field of sensors and magnetic refrigeration.…”