Magnetic Properties of the Ferromagnetic Shape Memory Alloys Ni50+xMn27−xGa23 in Magnetic Fields

• Main Authors: Takuo Sakon, Kohei Otsuka, Junpei Matsubayashi, Yuushi Watanabe, Hironori Nishihara, Kenta Sasaki, Satoshi Yamashita, Rie Y. Umetsu, Hiroyuki Nojiri, Takeshi Kanomata
• Format: Article
• Language: English
• Published: MDPI AG 2014-05-01
• Series: Materials
• Subjects: shape memory alloys; thermal strain; magnetization; magnetic properties; magnetic field; itinerant electron ferromagnet
• Online Access: http://www.mdpi.com/1996-1944/7/5/3715

Thermal strain, permeability, and magnetization measurements of the ferromagnetic shape memory alloys Ni50+xMn27−xGa23 (x = 2.0, 2.5, 2.7) were performed. For x = 2.7, in which the martensite transition and the ferromagnetic transition occur at the same temperature, the martensite transition starting temperature TMs shift in magnetic fields around a zero magnetic field was estimated to be dTMs/dB = 1.1 ± 0.2 K/T, thus indicating that magnetic fields influences martensite transition. We discussed the itinerant electron magnetism of x = 2.0 and 2.5. As for x = 2.5, the M4 vs. B/M plot crosses the origin of the coordinate axis at the Curie temperature, and the plot indicates a good linear relation behavior around the Curie temperature. The result is in agreement with the theory by Takahashi, concerning itinerant electron ferromagnets.