Effect of magnetic ordering on the stability of Ni–Mn–Ga(–Co–Cu) alloys along the tetragonal deformation path

0481170 - FZÚ 2018 RIV US eng J - Journal Article
Zelený, M. - Sozinov, A. - Björkman, T. - Straka, Ladislav - Heczko, Oleg - Nieminen, R.M.
Effect of magnetic ordering on the stability of Ni–Mn–Ga(–Co–Cu) alloys along the tetragonal deformation path.
IEEE Transactions on Magnetics. Roč. 53, č. 11 (2017), s. 1-6, č. článku 1700306. ISSN 0018-9464. E-ISSN 1941-0069
R&D Projects: GA ČR GA16-00043S
Institutional support: RVO:68378271
Keywords : Ab initio calculation * Curie temperature * magnetic shape memory * Ni–Mn–Ga
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
Impact factor: 1.467, year: 2017

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 (PM) state is described by disordered local moment approach. In stoichiometric Ni2MnGa alloy, the total energy profile along the tetragonal deformation path differs between ferromagnetic (FM) ground state and PM 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 FM interaction. In PM state it can be stabilized by partial substitution of Ni by Co or by partial substitution of Mn/Ga by Cu. Energy difference between PM and FM state EPM-FM can be used for qualitative estimation of Curie temperature TC.

Permanent Link: http://hdl.handle.net/11104/0276827