Pyridine intercalated Bi2Se3 heterostructures: controlling the topologically protected states

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Chemistry

Background:

• Bismuth selenide (Bi2Se3) is a topological insulator with unique electronic properties.
• Van der Waals (vdW) gaps in layered materials offer sites for intercalation and property tuning.
• Controlling topological states is crucial for next-generation electronic devices.

Purpose of the Study:

• To investigate the effects of pyridine molecule intercalation on Bi2Se3 electronic and topological properties.
• To explore the formation of trivial/topological heterojunctions and their interfacial states.
• To examine the influence of external pressure on the topological phase of intercalated Bi2Se3.

Main Methods:

• Ab initio simulations were employed to model the system.
• Electronic structure calculations were performed for pristine and intercalated Bi2Se3.
• The impact of varying interlayer distances due to intercalation and pressure was analyzed.

Main Results:

• Pyridine intercalation increases interlayer separation, suppressing parity inversion and creating a trivial insulating region.
• A trivial/topological heterojunction (py-Bi2Se3/Bi2Se3) exhibits topologically protected metallic states at the interface.
• Applying compressive pressure reduces interlayer distance, shifting metallic states and restoring an insulating phase.

Conclusions:

• Pyridine intercalation in Bi2Se3 enables the creation of heterostructures with embedded topological metallic channels.
• External pressure provides a tunable mechanism to control the on/off switching of these topological metallic states.
• This research opens avenues for designing novel topological heterostructures and superlattices with switchable properties.