Open AccessTheoretical design of tetragonal rare-earth-free alloys with high magnetisation and high magnetic anisotropy
Author(s) -
Motokazu Tsujikawa,
Yuito Mitsuhashi,
Masamitsu Shirai
Publication year - 2020
Publication title -
japanese journal of applied physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 129
eISSN - 1347-4065
pISSN - 0021-4922
DOI - 10.35848/1347-4065/ab87dd
Subject(s) - tetragonal crystal system , condensed matter physics , curie temperature , magnetization , materials science , ferromagnetism , ferrimagnetism , magnetic anisotropy , anisotropy , saturation (graph theory) , coercivity , phase (matter) , chemistry , magnetic field , physics , optics , quantum mechanics , mathematics , organic chemistry , combinatorics
Tetragonal alloys, such as D 0 22 -Mn 3 Ga, are potential candidates for rare-earth free permanent magnets due to their high Curie temperature and uniaxial magnetic anisotropy. For high-performance permanent magnets, high saturation magnetisation is necessary. However, the saturation magnetisation of D 0 22 -Mn 3 Ga is small due to ferrimagnetic ordering. We investigated the possibility of developing ferromagnetic Heusler alloys with high magnetic anisotropy and saturation magnetisation using the first-principles calculation. We focused on the effects of Fe substitution for Mn in D 0 22 -Mn 3 Ga as well as the consequent volume expansion; the ferromagnetic tetragonal XA phase is stabilized in Fe 2 MnGa by an 8% volume expansion. This tetragonal XA -Fe 2 MnGa has desirable properties for a high-performance permanent magnet, such as high magnetisation (1350 emu cc −1 ), perpendicular magnetic anisotropy (2.12 MJ m −3 ), and Curie temperature (1047 K). In addition, the substitution of Sn and increasing the Ga composition in the Fe 2 MnGa alloy results in volume expansion, which stabilizes the ferromagnetic tetragonal XA phase.