Optical spectrum of $n$-type and $p$-type monolayer MoS$_2$ in the presence of proximity-induced interactions
In this paper, we examined the effects of proximity-induced interactions such as Rashba spin-orbit coupling (SOC) and effective Zeeman fields (EZFs) on the optical spectrum of $n$-type and $p$-type monolayer (ML)-MoS$_2$. The optical conductivity is evaluated using the standard Kubo formula under Random phase approximation (RPA) with including the effective electron-electron interaction. It has been found that there exists two absorption peaks in $n$-type ML-MoS$_{2}$ and two knife shaped absorptions in $p$-type ML-MoS$_{2}$ which are contributed by the inter-subband spin flip electronic transitions within conduction and valence bands at valleys $K$ and $K'$ with a lifted valley degeneracy. The optical absorptions in $n$-type and $p$-type ML-MoS$_{2}$ occur in THz and infrared radiation regimes and the position, height, and shape of them can be effectively tuned by Rashba parameter, EZFs parameters, and carrier density. The interesting theoretical predictions in this study would be helpful for the experimental observation of the optical absorption in infrared to THz bandwidths contributed by inter-subband spin flip electronic transitions in a lifted valley degeneracy monolayer transition metal dichalcogenides (ML-TMDs) system. The obtained results indicate that ML-MoS$_{2}$ with the platform of proximity interactions make it a promising infrared and THz material for optics and optoelectronics.