Tunable Magneto-Optical Kerr Effect in Gated Monolayer Graphene in Terahertz Region

Magneto-optical Kerr effect (MOKE) as a simple but powerful method can be used for probing physical properties from quantum effects to classical magnetoplasmonics. Here, we study voltage-dependent MOKE for terahertz (THz) applications in graphene. The results suggest that in quantum regime the reflectivity spectrum mainly carry the real part of the diagonal conductivity information, while Kerr rotation spectrum carry the real part of Hall conductivity information without Fabry-Perot (FP) interferences. FP from substrates can bring apparent shape change and different informations for the interband transitions originating from the phase change, while no evident change for intraband transitions. In classic regime, the giant magnetoplasmons effect of graphene and the synergetic effect of magnetic and electric modulation can result in broad-band manipulation. It also suggests that high carrier density but limited magnetic field is needed for maximum Kerr rotation. Our results reveal potential THz applications with gated graphene based on MOKE.