Localization versus delocalization of d-states within the $$\hbox {Ni}_{{2}}$$MnGa Heusler alloy

• Published in: Scientific reports Vol. 12; no. 1
• Main Authors: Janovec, Jozef, Zelený, Martin, Heczko, Oleg, Ayuela, Andrés
• Format: Journal Article
• Language: English
• Published: 29-11-2022
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-022-23575-1

We present calculations based on density-functional theory with improved exchange-correlation approaches to investigate the electronic structure of
$$\hbox {Ni}_2$$
Ni
2
MnGa magnetic shape memory alloy prototype. We study the effects of hybrid functionals as well as a Hubbard-like correction parameter U on the structural, electronic and magnetic properties of the alloy. We show that the previously successful application of U on Mn should be extended by including U on Ni to describe the
d
localized electrons more accurately and in better agreement with experiments. The bonding interactions within this intermetallic alloy are analysed including the role of non-transition metal. We found that the strongest and most stabilizing bond is formed between the Ga–Ni pairs due to the delocalized
s
–
s
and
p
–
s
orbital hybridization. Our findings suggest that minimization of the over-delocalization error introduced by standard semi-local exchange-correlation functionals leads to a better description of the
$$\hbox {Ni}_2$$
Ni
2
MnGa alloy. Furthermore we propose that the experimental total magnetic moment of Ni–Mn–Ga alloys could be increased after carefully selected heat treatment procedures.