First Principle Study of Electronic Structure, Magnetic and Linear Properties of FeCoSi  Half Heulser Alloy

Abstract

This research provides an in-depth first principle analysis of the electronic, magnetic, and linear optical characteristics of the CoFeSi half-Heusler alloy. Utilizing Density Functional Theory (DFT) within the Quantum ESPRESSO environment and applying the PBE-GGA exchange-correlation functional, the study examines the material’s fundamental physics. CoFeSi is found to settle into a hexagonally distorted   structure after relaxation with optimized lattice dimensions of a = b = 5.59 Å and c = 6.95 Å. The electronic data indicates a standard metallic ferromagnetic state, characterized by a saturation magnetization of 5.53 μB and a total magnetic moment of 4.89 μB. Notably, the calculated spin polarization of roughly 15% suggests that the alloy does not exhibit complete half-metallicity. The Density of States is finite at the Fermi level in both spin channels indicating a spin polarized behaviour, while the projected Density of states shows that the dorminant contribution is from Co and Fe 3d orbitals, while Si/p states contributes less. Optical assessments across a 0–10 eV spectrum highlight a maximum absorption near 8 eV (~10⁶ cm⁻¹), a peak refractive index of 2.80 at 2 eV, and a static extinction coefficient of approximately 9.20. With an optical conductivity peaking at 3150 Ω⁻¹cm⁻¹ and a real dielectric function near −83, while imaginary dielectric function reached a peak at 0ev, which indicates potentials of CoFeSi for tunable spintronics optoelectronics and plasmonic applications