Applied Journal of Physical Science

This study employs spin-polarised density functional theory (GGA PBE+U) to investigate the structural, electronic, and magnetic properties of Fe-substituted Cu₂O at a nominal dopant concentration of 2.08%, corresponding to one Fe atom in a 2×2×2 supercell (48 atoms). The optimised lattice constant of pristine Cu₂O (4.252 Å) agrees closely with the experimental JCPDS value (4.2696 Å), with a relative error of only 0.4%. Upon Fe substitution, the lattice constant decreases to 4.018 Å, and the Fe–O bond length (1.804 Å) becomes shorter than the original Cu–O bond (1.841 Å), indicating local lattice contraction. The negative formation energy (–7.67 eV) confirms that Fe incorporation is thermodynamically favourable under Cu-poor growth conditions. While a local bond angle change from 109.47° to 104.80° is observed, the overall cubic symmetry of Cu₂O is preserved. Pristine Cu₂O shows symmetric spin channels with a semiconducting gap and no net spin polarisation. In contrast, Fe substitution introduces Fe 3d-derived impurity states near the Fermi level, leading to strong spin asymmetry: one spin channel becomes metallic while the other remains semiconducting, resulting in near-half-metallic behaviour. Projected density of states reveals strong hybridisation between Fe 3d and O 2p orbitals, which underlies the observed exchange splitting and spin polarisation. The computed total magnetic moment is approximately 3.05 μB per Fe atom, largely localised on the Fe site with minor polarisation on neighbouring O and Cu atoms, which is a hallmark of dilute magnetic semiconductors. Comparison of ferromagnetic (FM) and antiferromagnetic (AFM) configurations shows that the FM state is lower in energy by 0.24 eV, establishing an FM ground state. Using the mean-field approximation, the Curie temperature is estimated to be about 185 K, suggesting that room-temperature ferromagnetism may be achievable with higher doping concentrations or co-doping strategies. These results highlight Fe-doped Cu₂O as a promising candidate for spintronic applications.