Abstract
We conduct a comprehensive investigation of the effect of an applied electric field on the optical and magneto-optical absorption spectra for AB-bt (bottom-top) bilayer silicene. The generalized tight-binding model in conjunction with the Kubo formula is efficiently employed in the numerical calculations. The electronic and optical properties are greatly diversified by the buckled lattice structure, stacking configuration, intralayer and interlayer hopping interactions, spin-orbital couplings, as well as the electric and magnetic fields ({E}_{z}hat{z}& {B}_{z}hat{z}). An electric field induces spin-split electronic states, a semiconductor-metal phase transitions and the Dirac cone formations in different valleys, leading to the special absorption features. The Ez-dependent low-lying Landau levels possess lower degeneracy, valley-created localization centers, peculiar distributions of quantum numbers, well-behaved and abnormal energy spectra in Bz-dependencies, and the absence of anti-crossing behavior. Consequently, the specific magneto-optical selection rules exist for diverse excitation categories under certain critical electric fields. The optical gaps are reduced as Ez is increased, but enhanced by Bz, in which the threshold channel might dramatically change in the former case. These characteristics are in sharp contrast with those for layered graphene.
Highlights
We concentrate our efforts to achieve a full understanding of the optical absorption spectra of bilayer silicene, being closely related to the electronic properties in the presence/absence of electric and magnetic fields
The spatial distribution of two electron spins when being transported by either spin-orbital coupling (SOC) or random impurity scattering constitutes a basis for modern spintronics and valleytronics
The valence and conduction bands are sensitive to an external electric field
Summary
Layered condensed-matter systems, with varied physical properties and many potential device applications, have so far attracted a great deal of experimental and theoretical attention[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23]. Examination of the fundamental physical properties of 2D materials, including their electronic, optical, transport, and Coulomb excitations, is very helpful in justifying their importance in the field of nanotechnology applications, such as the novel designs of nano-electronics, nano-optics, and energy storage[24,25,26,27,28,29,30]. The spatial distribution of two electron spins when being transported by either spin-orbital coupling (SOC) or random impurity scattering constitutes a basis for modern spintronics and valleytronics Such characteristics are taken into account in the design of next-generation ultrafast transistors for on-chip image processing in photo-detection. Novel phenomena in Coulomb excitations are utilized to design transportable, compact, low-power and reconfigurable devices in security and wideband optical communications
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