Topological insulator state in gated bilayer silicene

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Topological insulators (TIs) possess unique electronic properties with potential applications in quantum computing and spintronics.
• Silicene, a silicon analog of graphene, offers tunable electronic properties through external stimuli.
• Rashba spin-orbit (SO) coupling plays a crucial role in realizing topological phases in low-dimensional materials.

Purpose of the Study:

• To investigate the topological insulator states in gated bilayer silicene under extrinsic Rashba SO coupling.
• To explore the influence of intrinsic SO and Rashba SO couplings on the topological phases.
• To examine the effect of a tilted electric field on the topological properties of bilayer silicene.

Main Methods:

• Theoretical investigation using first-principles calculations.
• Analysis of electronic band structure and topological invariants.
• Modeling the effects of external electric fields and SO couplings.

Main Results:

• Bilayer silicene transitions from a band insulator (BI) to a strong topological insulator (TI) phase with increasing Rashba SO coupling.
• The strong TI phase exhibits robust spin and valley filtering.
• An in-plane electric field induces interlayer Rashba SO coupling, driving the system back to a BI phase.

Conclusions:

• Gated bilayer silicene hosts tunable topological phases controlled by Rashba SO coupling.
• The system's topological state can be switched between TI and BI phases using electric fields.
• These findings suggest potential applications for silicene in novel nanoelectronic devices.