Collective excitations in spin-polarized bilayer graphene

We calculate the plasmon frequency omega and damping rate gamma 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. We also find that the damping rate and the shape of gamma as a function of q depend strongly on P. The increase in carrier density decreases significantly both plasmon frequency and damping rate independently of the spin polarization. The numerically calculated critical wave vector, at which the plasmon dispersion curve hits the edge of electron-hole continuum, decreases with P and can be used to experimentally determine the degree of spin polarization.

Automated summary

This study calculates the plasmon frequency and damping rate of plasma oscillations in a spin-polarized bilayer graphene system. It shows that the degree of spin polarization has a negligible effect on the long wavelength plasmon frequency but affects the damping rate and frequency changes with increasing spin polarization. Moreover, an increase in carrier density significantly decreases both the plasmon frequency and damping rate, while the critical wave vector decreases with spin polarization and can be used to experimentally determine the degree of spin polarization.