Effects of the Short-Range Exchange Interaction on Plasmon Modes of Monolayer Black Phosphorous

We theoretically study the anisotropic collective plasmon excitations of monolayer black phosphorus beyond the random phase approximation by considering the short-range exchange interaction between the electrons. By applying the Hubbard local field correction to the dielectric function, we calculate the plasmon dispersion relation and loss function at room temperature. Numerical results show that the plasmon mode energies decrease along both main crystallographic directions when the Hubbard local field correction factor is taken into account. This effect is slightly stronger in the direction of lighter mass. Furthermore, we investigate the effect of local field on the loss function at different electron densities and obtain that the shift in plasmon frequency with density variation is smaller when the exchange interaction is included. Our findings may be useful for future studies on phosphorene-based nano-optic and plasmonic devices.