Engineering topological states in a two-dimensional honeycomb lattice

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Chemistry

Background:

• Spin-orbit coupling (SOC) and magnetism are crucial for exotic electronic states.
• Honeycomb lattices host diverse topological phenomena, including the quantum anomalous Hall effect.
• Understanding the interplay between SOC and magnetism is key to designing novel topological materials.

Purpose of the Study:

• To investigate the interplay between spin-orbit coupling and magnetism in honeycomb systems.
• To identify the mechanisms leading to both topologically trivial and nontrivial states.
• To provide a theoretical guideline for manipulating topological states in two-dimensional materials.

Main Methods:

• First-principles calculations to model electronic structures.
• Tight-binding model analysis to understand band structures.
• Investigating magnetic materials (e.g., CrBr3, CrCl3, VBr3) and heavy-metal-based materials (e.g., BaTe(111)-supported plumbene).

Main Results:

• Two types of topologically trivial states were identified: one from coexisting non-Dirac and Dirac bands in the same spin channel, and another from destructive coupling between spin channels in heavy-metal systems.
• Topologically nontrivial states can be achieved by modifying band dispersion in magnetic monolayers or enhancing spin splitting in heavy-metal systems.
• Specific examples like alkali metal doped CrBr3 and half-iodinated silicene demonstrate pathways to nontrivial states.

Conclusions:

• The interplay of SOC and magnetism dictates topological states in honeycomb lattices.
• Theoretical guidelines are established for realizing nontrivial topological states by manipulating band structures and spin splitting.
• This work offers a framework for designing advanced topological materials with tailored electronic properties.