Density functional theory analysis of spin polarization and 4f-state magnetism in holmium doped MgZnO heterostructures via Fermi level modulation

Abstract

The structural, electronic, and magnetic properties of Holmium- and Magnesium-doped ZnO were investigated using density functional theory (DFT) for the Zn₁₇Mg₂Ho₁O₁₆ lattice. Mg doping was found to slightly expand the lattice (a = 3.250 Å → 3.254 Å) and reduce the calculated bandgap from 0.758 eV to 0.216 eV, thereby influencing the electrical conductivity. Ho incorporation shifted the Fermi level into the conduction band and induced strong ferromagnetism via highly spin-polarized 4f electrons, with 96.5% of the total magnetic moment concentrated in the spin-up channel and a net moment of 4.0 µ_B. Holmium doping also caused lattice contraction (a = 3.065 Å) and is predicted to enhance photoconductivity. These results suggest that Mg incorporation contributes to lattice expansion and electrical conductivity, while Ho doping introduces pronounced spin polarization, making Ho–Mg–ZnO a promising candidate for spintronic and magneto-optical applications.