ABSTRACT: The electronic and magnetic properties of lanthanide-doped GaN monolayers (Ln = La, Pr, Nd, Pm, Eu, and Gd) have been systematically investigated using density functional theory within the GGA-PBE approximation. Our results demonstrate that all Ln dopants except La introduce spin polarization and half-semiconductor behavior into the GaN monolayer. The observed magnetism primarily arises from unpaired 4f electrons, yielding magnetic moments of 2.0, 3.0, 4.0, 6.0, and 7.0 μB for Pr, Nd, Pm, Eu, and Gd, respectively. While La-, Pr-, and Gd-doped systems retain the indirect band gap characteristic of pristine GaN, an indirect-to-direct band gap transition occurs under biaxial tensile strains exceeding 2%. In contrast, Nd, Pm, and Eu doping directly induce a direct band gap without a
