Controlling Topological States in Topological/Normal Insulator Heterostructures

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Topological insulators (TIs) possess unique surface states with potential for novel electronic applications.
• Understanding interface states in topological/normal insulator (TI/NI) heterostructures is crucial for harnessing their properties.

Purpose of the Study:

• To systematically investigate the nature of nontrivial interface states in TI/NI heterostructures.
• To explore the tunability of interface properties for potential device applications.

Main Methods:

• Utilized first-principles calculations based on density functional theory (DFT).
• Employed a novel scheme to construct ab initio effective Hamiltonian matrices.
• Studied realistic system sizes with precise control over parameters like band alignment, normal insulator gap, and spin-orbit coupling.

Main Results:

• Demonstrated interface gap tunability in IV-VI compounds by controlling normal insulator thickness.
• Verified the preservation of an in-plane spin texture in the interface-gaped topological states.

Conclusions:

• The interface gap in TI/NI heterostructures is tunable, offering pathways for novel device design.
• Preserved in-plane spin texture in topological interface states is confirmed.