Photoelectric and Magnetic Variation of Transition Metal-Doped Monolayer TiS2: A First-Principles Calculation

In this paper, a first-principles study of the stability, electronic structure, and magnetic and optical properties of transition metal (TM)-doped monolayer TiS2 systems has been carried out based on the GGA + U methodology under density functional theory. Formation energies, binding energies, phonon spectra, and molecular dynamics calculations indicate the stability of the systems. The Mn-, Fe-, and Co-doped systems exhibit magnetic narrow-band semiconductor properties, with Mn doping inducing the most sizable net magnetic moments. The V- and Mo-doped systems demonstrate magnetic-metallic properties, and incorporating Nb, Ta, and W gives the monolayer TiS2 system semi-metallic properties. The absorption band edges of the doped systems are all redshifted, in which V and Mo doping produces strong orbital hybridization at the Fermi energy level, generates new dielectric peaks in the low-energy region, and extends the absorption range of infrared light, which significantly enhances the optical response of the system. This study provides a theoretical reference for the application of monolayer TiS2 in nanospin and optoelectronics.