Substrate dependent terahertz magneto-optical properties of monolayer WS₂

Terahertz (THz) magneto-optical (MO) properties of monolayer (ML) tungsten disulfide (WS₂), placed on different substrates and subjected to external magnetic fields, are studied using THz time-domain spectroscopy (TDS). We find that the THz MO conductivity exhibits a nearly linear response in a weak magnetic field, while a distinctly nonlinear/oscillating behavior is found in strong magnetic fields owing to strong substrate-induced random impurity scattering and interactions. The THz MO response of ML WS₂ depends sensitively on the choice of the substrates, which we trace back to electronic localization and the impact of the substrates on the Landau level (LL) spectrum. Our results provide an in-depth understanding of the THz MO properties of ML WS₂/substrate systems, especially the effect of substrates, which can be utilized to realize atomically thin THz MO nano-devices.