Shape memory ferromagnets
A.N. Vasil’ev a, b, c,
V.D. Buchel’nikov d,
T. Takagi e,
V.V. Khovailo f, g,
E.I. Estrin h
a Department of Theoretical Physics, Institute of Physics, St. Petersburg State University, ul. Ulyanovskaya 1, Petrodvorez, St. Petersburg, 198904, Russian Federation
b Lomonosov Moscow State University, Vorobevy Gory, Moscow, 119991, Russian Federation
c Lomonosov Moscow State University, Faculty of Physics, Leninskie Gory 1 build. 2, Moscow, 119991, Russian Federation
d Chelyabinsk State University, ul. Bratev Kashirinykh 129, Chelyabinsk, 454021, Russian Federation
e Institute of Fluid Science, Tohoku University, Sendai, Japan
f National Institute of Advanced Industrial Science and Technology, Tohoku Center 4-2-1, Nigatake, Miyagino-ku, Sendai, 983-8551, Japan
g Institute of Radio Engineering and Electronics, Russian Academy of Sciences, ul. Mokhovaya 11, Moscow, 125009, Russian Federation
h G.V. Kurdyumov Institite of Metal Science and Physics, State Research Centre of the Russian Federation, I.P. Bardin Central Research Institute of Ferrous Metallurgy, 2-ya Baumanskaya ul. 9/23, Moscow, 105005, Russian Federation
In ferromagnetic alloys with shape memory large reversible strains can be obtained by rearranging the martensitic domain structure by a magnetic field. Magnetization through displacement of domain walls is possible in the presence of high magnetocrystalline anisotropy, when martensitic structure rearrangement is energetically favorable compared to the reorientation of magnetic moments. In ferromagnetic Heusler alloys Ni2+xMn1-xGa the Curie temperature exceeds the martensitic transformation temperature. The fact that these two temperatures are close to room temperature offers the possibility of magnetically controlling the shape and size of
ferromagnets in the martensitic state. In Ni2+xMn1-xGa single
crystals, a reversible strain of ~6% is obtained in fields of ~1 T.
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