Integer quantum Hall conductivity and longitudinal conductivity in silicene under the electric field and magnetic field

We investigate the integer Hall conductivity and longitudinal conductivity of silicene under the magnetic field, electric field, and exchange field in this letter. We focus not only on the low-temperature and $\delta$-function impurities (i.e., independent of the scattering momentum) case, which only exist the intra-Landau level transition, but also on the case of inter-Landau level transition which also with the non-elastic scattering. The resulting longitudinal conductivity is very different with the intra-Landau level one at low-temperature. The exprssions of the Hall conductivity, longitudinal conductivity, valley contributed Hall conductivity, and the spin or valley Hall conductivity, are deduced in this letter. We also compute the dynamical polarization under the magnetic field which is a important quantity and has many exciting and novel properties, and with the screened scattering due to the charged impurities. The polarization function here is also related to the Landau level index under the magnetic field, and shows step-like feature rather than the logarithmically divergenas which appears for the zero-magnetic field case, and it's also naturally related to the conductivity in silicene. The generalized Laguerre polynomial is used in both the longitudinal conductivity and dynamical polarization function under magnetic field

Dynamical polarization and the optical response of silicene and related materials

We discuss the dynamical polarization, optical response in low-frequency regime under in-plane polarized driving field of the silicene. The dynamical polarization, dielectric function, and absorption of radiation in infrared region are obtained and shown in the ${\bf q}\sim\omega$ space, and they are distinguishing for the cases of chemical potential larger than the band gap and smaller than the band gap. The optical properties of silicene and the related group-V and group-VI materials: MoS$_{2}$ and black phosphorus are explored through the first-principle study. The plasmon which damped into the electron-hole pair in the single-particle excitation regime is also mentioned. The spin/valley polarized electron-hole pairs can be formed through that way, especially for the high-energy $\pi$-plasmon which begin to damp at the small ${\bf q}$-limit. The anisotropic effects induced by the warping structure or charged impurity, and the anisotropic polarization induced by the polarized incident light are also discussed. Our result exhibits the great potential in the optoelectronic applications of the materials we discussed