Plasmon modes in-layer silicene structures.

We investigate the plasmon properties in-layer silicene systems consisting of, up to 6, parallel single-layer silicene (SLS) under the application of an out-of-plane electric field, taking into account the spin-orbit coupling within the random-phase approximation. Numerical calculations demonstrate thatundamped plasmon modes, including one in-phase optical (Op) and (- 1) out-of-phase acoustic (Ac) modes, continue mainly outside the single-particle excitation area of the system. As the number of layers increases, the frequencies of plasmonic collective excitations increase and can become much larger than that in SLS, more significant for high-frequency modes.

Collective excitations in spin-polarized bilayer graphene.

We calculate the plasmon frequency ω and damping rate γ of plasma oscillations in a spin-polarized BLG system. Using the long wavelength approximation for dynamical dielectric function, we obtain an analytical expression for plasmon frequency showing that degree of spin polarization P has negligible effect on the long wavelength plasmon frequency. Numerical calculations demonstrate that the plasmon frequency increases (decreases) noticeably (slightly) with the increase in spin polarization in large (small) wave-vector q region.