First‐Principles Prediction of Spin‐Selective Optical Properties in Two‐Dimensional Ferromagnetic V ₂ CBr ₂ for Ultraviolet Spintronics

The spin‐dependent electronic structure and magneto‐optical properties of monolayer V ₂ CBr ₂ , a bromine‐functionalised vanadium carbide MXene, were systematically investigated using spin‐polarised density functional theory with Hubbard correction (DFT +  U ) implemented in the Quantum ESPRESSO package. Employing the GGA‐PBE exchange‐correlation functional ( U  = 4.0 eV on V 3d orbitals) and DFT‐D3 van der Waals corrections, we demonstrate that V ₂ CBr ₂ crystallises in a hexagonal P1 structure and exhibits a robust antiferromagnetic ground state with metallic conduction in both spin channels. Spin‐resolved band structures and partial density of states reveal pronounced exchange splitting (~1–2 eV) dominated by vanadium d orbitals, flat bands near the K and H points, and van Hove singularities that generate strong spin polarisation at the Fermi level. Comprehensive spin‐oriented optical spectra dielectric function, absorption coefficient, reflectivity, refractive index, optical conductivity, and energy‐loss function—computed within the random‐phase approximation up to 90 eV show clear asymmetries between up‐spin and down‐spin channels. The up‐spin channel dominates low‐energy absorption and reflectivity, while both spins exhibit a prominent plasmon peak near 16 eV and a secondary resonance at ~40 eV. These results establish V ₂ CBr ₂ as a promising 2D platform for spin‐selective ultraviolet optoelectronics, magneto‐plasmonics, and spintronic devices, offering quantitative guidance for experimental realisation through mechanical exfoliation or heterostructure integration.