A1 Journal article (refereed), original research

Effect of Magnetic Ordering on the Stability of Ni-Mn-Ga(-Co-Cu) Alloys along the Tetragonal Deformation Path


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Publication Details
Authors: Zeleny Martin, Sozinov Alexei, Björkman Torbjörn, Straka Ladislav, Heczko Oleg, Nieminen Risto M.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Publication year: 2017
Language: English
Related Journal or Series Information: IEEE Transactions on Magnetics
Volume number: 53
Issue number: 11
ISSN: 0018-9464
eISSN: 1941-0069
JUFO-Level of this publication: 1
Open Access: Not an Open Access publication

Abstract

The influence of magnetic ordering on the stability of Ni-Mn-Ga(-Co-Cu)
Heusler alloys is investigated using the first-principles exact
muffin-tin orbital method in combination with the coherent-potential
approximation. The paramagnetic state is described by disordered local
moment approach. In stoichiometric Ni2MnGa alloy,
the total energy profile along the tetragonal deformation path differs
between ferromagnetic ground state and paramagnetic state with high
energy, where cubic structure of austenite exhibits lower total energy
than tetragonally distorted structure of martensite. Martensitic
structure is stabilized in ground state by ferromagnetic interaction. In
paramagnetic state it can be stabilized by partial substitution of Ni
by Co or by partial substitution of Mn/Ga by Cu. Energy difference
between paramagnetic and ferromagnetic state
ΔEPM-FM can be used for qualitative estimation of
Curie temperature TC. Since Co doping to Ni
sublattice slightly increases ΔEPM-FM, the
TC should also increase, which corresponds to
experimental findings. Analogically, Cu doping to Mn sublattice strongly
decrease ΔEPM-FM, which corresponds to strong
decreasing of TC also confirmed experimentally.
For Cu doping in Ga sublattice the decrease in TC
is weaker.


Last updated on 2018-19-10 at 07:55