First-Principles Investigation of the Structural, Magnetic, Electronic and Optical Properties of FeMnScB Quaternary Heusler Alloy

The structural, magnetic, electronic and optical properties of FeMnScB quaternary Heusler alloys (QHA) were investigated using spin-polarized density functional theory (DFT) within the full-potential linearized augmented plane wave (FP-LAPW) method considering the Perdew–Burke–Ernzerhof Generalized Gradient Approximation (PBE-GGA) exchange-correlation functional using WIEN2K. Ferromagnetic (FM) configurations are energetically more favorable than antiferromagnetic (AFM) and nonmagnetic (NM) states, according to total energy calculations, establishing the FM phase as a magnetic ground state. Excellent structural stability is indicated by the optimized equilibrium lattice parameter of 5.7559 Å and a bulk modulus of 165.4369 GPa. The Slater–Pauling rule is followed by the computed total magnetic moment of 3.00[Formula: see text] [Formula: see text] B per formula unit, and the magnetic moment shows strong magnetic stability. A highly spin-polarized electronic state with ∼99.33% spin polarization at the Fermi level and a small minority-spin energy gap of 0.31[Formula: see text]eV is revealed by electronically computed band structure, indicating near-half-metallic behavior. Fe-3d and Mn-3d orbitals dominate the magnetic and electronic properties, according to orbital-resolved density of states (DOS) studies, whereas Sc mainly serves as an electron donor and B enhances chemical bonding and structural stability through p–d hybridization. Throughout the visible and ultraviolet (UV) spectrum, optical constants show substantial absorption coefficients (∼10 4 [Formula: see text]cm[Formula: see text], notable optical conductivity, moderate reflectivity and a prominent dielectric response, all of which point to effective photon absorption and carrier activation. FeMnScB is a promising multifunctional QHA for advanced spintronic, magneto-optoelectronic, UV photonic and photovoltaic applications due to its structural durability, intrinsic ferromagnetism, high spin polarization and broadband optical activity.