Geometry- and field-diversified electronic and optical properties in bilayer silicene

TL;DR

This paper develops a generalized tight-binding model to explore the diverse electronic and optical properties of AB-bt bilayer silicene, revealing complex behaviors influenced by structure, fields, and interactions, with implications for optoelectronic applications.

Contribution

It introduces a comprehensive model capturing the effects of structure, fields, and couplings on bilayer silicene's properties, highlighting novel electronic and optical phenomena.

Findings

Diverse dispersions and band structures including linear, parabolic, and constant-energy loops.

Rich Landau Level spectra with unique degeneracy and localization features.

Pronounced magneto-absorption peaks with no specific selection rules.

Abstract

The generalized tight-binding model has been developed to thoroughly explore the essential electronic and optical properties of AB-bt bilayer silicene. They are greatly diversified by the buckled structure, stacking configuration, intralayer and interlayer hopping integrals, spin-orbital couplings; electric and magnetic fields (${E_z\hat z}$ $\&$ ${B_z\hat z}$). There exist the linear, parabolic and constant-energy-loop dispersions, multi-valley band structure and semiconductor-metal transition as $E_z$ varies. The $E_z$-dependent magnetic quantization exhibits the rich and unique Landau Levels (LLs) and magneto-optical spectra. The LLs have the lower degeneracy, valley-created localization centers, unusual distributions of quantum numbers, well-behaved and abnormal energy spectra in $B_z$-dependences, and the absence of anti-crossing behavior. A lot of pronounced magneto-absorption peaks occur at a very narrow frequency range, being attributed to diverse excitation categories. They have no specific selection rules except that the Dirac-cone band structures are driven by the critical electric fields. The optical gaps are reduced by $E_z$, but enhanced by $B_z$, in which the threshold channel might dramatically change in the formed case. The above-mentioned characteristics are in sharp contrast with those of layered graphenes.