Hole induced half-metallic 2H VSe2 thin film with high Curie temperature and optical transparency

In low-dimensional semiconductor systems, carrier doping can effectively tune the electronic band structure, leading to significant impacts on magnetic properties. In this study, we investigate the influence of hole doping on 2H VSe2 films by varying their thickness from bilayer to four-layer configurations. The pristine 2H VSe2 film exhibits layer-to-layer antiferromagnetic (AFM) state, but through hole carrier doping, we successfully switch this state to a ferromagnetic (FM) configuration. Notably, the critical hole carrier doping concentration is found to be thickness-dependent. For instance, in bilayer films, the critical hole doping concentration is approximately 1.25 × 1020/cm3, while in four-layer films, it increases to 6.75 × 1020/cm3. Furthermore, our investigations reveal the emergence of a half-metallic state due to hole doping in all systems. Although the critical temperature exhibits a consistent decrease with increasing layer thickness, remarkably high Curie temperatures are observed. Specifically, we calculate Curie temperatures of 600 K, 570 K, and 550 K for bilayer, trilayer, and four-layer films, respectively. In addition to these magnetic properties, we explore the optical characteristics of 2H VSe2 films. The four-layer film has a large refractive index of 3.2 near the blue light frequency. Moreover, the 2H VSe2 films exhibit optically transparent features in the visible frequency range. These results may indicate that the 2H VSe2 system can be utilized for potential optoelectronic devices based on magnetic materials.