Bridge constant and atom between theoretical and experimental magnetism in Ni₂MnSb Heusler alloy: DFT and EFT studies

ABSTRACT

Ni₂MnSb Heusler alloy is modelled and its magnetic properties are investigated by means of the effective field theory (EFT) developed by Kaneyoshi. Furthermore, the structural and electronic properties are performed by using density functional theory (DFT). According to DFT, with the help of volume-energy optimisation curves, the ferromagnetic (FM) state is more stable in energetic than the non-magnetic (NM) state. The value of the lattice constant obtained in this stable FM phase is a^DFT =6.03Å which confirms the experimental results reported by Ak et al. (a^Exp = 5.9861Å). According to EFT, we obtain a bridge constant (k_b) for fitting the theoretical and experimental results of Ni₂MnSb as k_b =127.5. When k_b < 127.5, the theoretical results are smaller than the experimental results. But, when k_b > 127.5, the theoretical results are higher than the experimental results of Ni₂MnSb. However, when k_b = 127.5, the theoretical results and experimental results are very close to each other and they are almost fitting. Additionally, we find the surface Manganese atoms (Mn2) are the bridge atoms (a_b) for fitting the theoretical and experimental M-T results of Ni₂MnSb Heusler alloys.

GRAPHICAL ABSTRACT

KEYWORDS:

• Ni₂MnSb Heusler alloy
• magnetic properties
• bridge constant
• bridge atom
• density functional theory
• effective field theory

Acknowledgments

The authors also would like to express their thanks to the Computer Center of Erciyes University.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Erciyes University Research Funds (Erciyes Üniversitesi) [grant number FBA-2019-9409].