Modeling of Structural, Electronic, and Magnetic Properties of 2D TlGaS2 Doped with a Magnetic Impurity

We perform a comprehensive DFT (density-functional theory) investigation of the electronic and magnetic properties of pristine and magnetically doped TlGaX2 (X is a chalcogen). Pristine TlGaX2 exhibits a well-defined band gap, a spin-degenerate density of states, and no intrinsic magnetic moments. Magnetic doping by transition-metal atoms induces pronounced structural distortions, introduces defect levels within the band gap, and generates strong spin polarization in both the electronic density of states and the band structure. The dopants create localized magnetic moments and modify the Fermi-level position, leading in several cases to a semiconductor–metal transition. These results demonstrate that magnetic dopants serve as an efficient mechanism for controlling the electronic structure and magnetic response of TlGaX2, providing a tunable platform for applications in spintronics and magnetically active functional materials. Magnetic properties of the layered structure of TlGaS2 doped with d transition metals (TMs) were theoretically studied using first-principles calculations. Using the DFT method within the generalized gradient approximation (GGA), it was shown that magnetism in TlGaS2 (monoclinic C2/c space group; no. 15) can be achieved by doping with transition metals TM = Cr, Mn, and Fe. The total magnetic moment in TlGaS2–TM (TM = Cr, Mn, and Fe) is primarily due to the 3d orbitals of the transition metals. Hybridization between the d orbital of TMs and the p orbitals of the TlGaS2 components was studied. DFT calculations with U = 6 eV on TM impurities were used to describe the strong electron–electron correlation. The magnetic moment of TM dopants during the transition from a low-spin to a high-spin state was studied. The DOS spectra and electronic structure of TlGaS2–TM were obtained, where doping transforms TlGaS2 into a magnetic material. These results can be used to experimentally study the magnetic properties of TlGaS2.