Spin and valley polarization of plasmons in silicene due to external fields

Abstract

The electronic properties of the novel two dimensional (2D) material silicene are strongly influenced by the application of a perpendicular electric field $E_z$ and of an exchange field $M$ due to adatoms positioned on the surface or a ferromagnetic substrate. Within the random phase approximation, we investigate how electron-electron interactions are affected by these fields and present analytical and numerical results for the dispersion of plasmons, their lifetime, and their oscillator strength. We find that the combination of the fields $E_z$ and $M$ brings a spin and valley texture to the particle-hole excitation spectrum and allows the formation of spin- and valley-polarized plasmons. When the Fermi level lies in the gap of one spin in one valley, the intraband region of the corresponding spectrum disappears. For zero $E_z$ and finite $M$ the spin symmetry is broken and spin polarization is possible. The lifetime and oscillator strength of the plasmons are shown to depend strongly on the number of spin and valley type electrons that form the electron-hole pairs.

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Cited by in corpus (8)

• Tuning the electronic structures of silicene and germanene by biaxial strain and electric field
• Plasmon properties and hybridization effects in Silicene
• Plasmon modes of a massive Dirac plasma, and their superlattices
• Magnetic Properties of Dirac Fermions in a Buckled Honeycomb Lattice
• Low-temperature linear transport of two-dimensional massive Dirac fermions in silicene: residual conductivity and spin/valley Hall effects
• Multi-component plasmons in monolayer MoS${}_2$ with circularly polarized optical pumping
• Electrically tunable magnetoplasmons in a monolayer of silicene or germanene
• Effects of electron-impurity scattering on density of states in silicene: impurity bands and band-gap narrowing