Browsing by Author "Salavati-fard, T."

Now showing 1 - 2 of 2

Open Access
Many-body effects due to the electron–electron interaction in silicene under an applied exchange field: the case of valley–spin coupling
(American Institute of Physics, 2020) Mirzae, M.; Vazifehshenas, T.; Salavati-fard, T.; Farmanbar, M.; Tanatar, Bilal
We investigate the many-body effects induced by the electron–electron interaction in a valley–spin-polarized silicene under a perpendicularly applied exchange field. We calculate the real and imaginary parts of the self-energy within the leading order dynamical screening approximation where the screened interaction is obtained from the random phase approximation. Our study on the valley- and spin-dependent real and imaginary parts of the self-energy indicates that the different coupled valley–spin subbands may exhibit distinct characteristics. Moreover, we obtain the corresponding spectral functions and find that the plasmaron and quasiparticle peaks have different spectral weights and broadenings in all states. Interestingly, it seems that there are clear dependencies for the position and broadening of the peaks on valley–spin indexes. In addition, we study the effect of the electron–electron interaction on the renormalized velocity in the on-shell approximation and show that the renormalized velocity in gapped states becomes greater, and in gapless states, it becomes smaller as the wave vector grows.
Open Access
Silicene dynamic optical response in the presence of external electric and exchange fields
(Institute of Physics Publishing Ltd., 2022-01-04) Mirzaei, M.; Vazifehshenas, T.; Salavati-fard, T.; Tanatar, Bilal
We investigate the dynamic optical transition of monolayer silicene in the presence of external electric and exchange fields within the low-energy tight-binding model. Applying external electric and exchange fields breaks the silicene band structure spin and valley degeneracies. Three phases of silicene corresponding to different strengths of perpendicular electric field with respect to the spin–orbit coupling (Δz < Δso, Δz = Δso and Δz > Δso) are considered. We obtain the spin-valley-dependent optical responses to the incoming circularly polarized light using the Kubo formula. We show and discuss how the magnitude and direction of the transverse and longitudinal optical responses of such a system change with the electric and exchange fields. Our calculations suggest that the intraband part of the longitudinal optical response as well as the initial point of the interband part have strong dependencies on the exchange field. Furthermore, we show that one of the spin subbands plays a dominant role in the response to polarized light. Depending on the type of incident light polarization, the dominant subband may change. Our results shed light on the relation between silicene dynamic optical responses and externally applied fields.