Magnetic properties and magnetostructural phase transitions in Ni2+xMn1-xGa shape memory alloys

Abstract

A systematic study of magnetic properties of Ni2+xMn1-xGa (0 \le x \le 0.19) Heusler alloys undergoing structural martensite-austenite transformations while in ferromagnetic state has been performed. From measurements of spontaneous magnetization, Ms(T), jumps ΔM at structural phase transitions were determined. Virtual Curie temperatures of the martensite were estimated from the comparison of magnetization in martensitic and austenitic phases. Both saturation magnetic moments in ferromagnetic state and effective magnetic moments in paramagnetic state of Mn and Ni atoms were estimated and the influence of delocalization effects on magnetism in these alloys was discussed. The experimental results obtained show that the shift of martensitic transition temperature depends weakly on composition. The values of this shift are in good correspondence with Clapeyron-Clausius formalism taking into account the experimental data on latent heat at martensite-austenite transformations.

7 pages, 8 figures

References in corpus (4)

• Coexistence of ferro- and antiferromagnetic order in Mn-doped Ni${}_2$MnGa
• Entropy change at the martensitic transformation in ferromagnetic shape memory alloys Ni_{2+x}Mn_{1-x}Ga
• Magnetic properties of Ni2.18Mn0.82Ga Heusler alloys with a coupled magnetostructural transition
• The magnetic field influence on magnetostructural phase transition in Ni2.19Mn0.81Ga

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