Publication detail
Origin of magnetocrystalline anisotropy in Ni-Mn-Ga-Co-Cu tetragonal martensite
ZELENÝ, M. STRAKA, L. RAMEŠ, M. SOZINOV, A. HECZKO, O.
English title
Origin of magnetocrystalline anisotropy in Ni-Mn-Ga-Co-Cu tetragonal martensite
Type
journal article in Web of Science
Language
en
Original abstract
We investigate the origin of magnetocrystalline anisotropy (MCA) in non-modulated martensite of Ni-Mn-Ga-Co-Cu exhibiting magnetic-field-induced strain up to 12%. Experiments as well as theoretical calculations using density functional theory show that Co and Cu doping or deviation from Ni2MnGa stoichiometry decreases the MCA. As follows from the calculations, the decrease of MCA is much stronger for Cu in Ga sublattice in comparison to Cu in Mn sublattice. The decreasing effect of Co on the MCA is only indirect caused by deficiency in Ni, which is the main element governing the MCA. For further insight, we calculated MCA and magnetic moment as a function of lattice tetragonality c/a. The MCA reaches a maximum at the same c/a where Ni magnetic moment is maximum. However, the tetragonality of equilibrium does not coincide with these maxima. Consequently, in contrast to common expectation, decreasing tetragonality from equilibrium can increase the MCA.
English abstract
We investigate the origin of magnetocrystalline anisotropy (MCA) in non-modulated martensite of Ni-Mn-Ga-Co-Cu exhibiting magnetic-field-induced strain up to 12%. Experiments as well as theoretical calculations using density functional theory show that Co and Cu doping or deviation from Ni2MnGa stoichiometry decreases the MCA. As follows from the calculations, the decrease of MCA is much stronger for Cu in Ga sublattice in comparison to Cu in Mn sublattice. The decreasing effect of Co on the MCA is only indirect caused by deficiency in Ni, which is the main element governing the MCA. For further insight, we calculated MCA and magnetic moment as a function of lattice tetragonality c/a. The MCA reaches a maximum at the same c/a where Ni magnetic moment is maximum. However, the tetragonality of equilibrium does not coincide with these maxima. Consequently, in contrast to common expectation, decreasing tetragonality from equilibrium can increase the MCA.
Keywords in English
Magnetic shape memory; Magnetocrystalline anisotropy; Ab initio calculations; Ni-Mn-Ga; Ni-Mn-Ga-Co-Cu
Released
01.06.2020
Publisher
ELSEVIER
Location
AMSTERDAM
ISSN
1873-4766
Volume
503
Number
-
Pages from–to
166522–-
Pages count
8
BIBTEX
@article{BUT163496,
author="Martin {Zelený} and Ladislav {Straka} and Michal {Rameš} and Alexei {Sozinov} and Oleg {Heczko},
title="Origin of magnetocrystalline anisotropy in Ni-Mn-Ga-Co-Cu tetragonal martensite",
year="2020",
volume="503",
number="-",
month="June",
pages="166522---",
publisher="ELSEVIER",
address="AMSTERDAM",
issn="1873-4766"
}