High-Temperature Quantum Anomalous Hall Insulators in Lithium-Decorated Iron-Based Superconductor Materials

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Chemistry

Background:

• Quantum anomalous Hall (QAH) insulators are crucial for topological quantum effects but are limited by low operating temperatures.
• Developing high-temperature QAH materials is essential for experimental advancements and practical applications.

Purpose of the Study:

• To discover novel two-dimensional (2D) materials exhibiting high-temperature QAH effects.
• To investigate the mechanism behind robust ferromagnetism and topological properties in these materials.

Main Methods:

• First-principles calculations were employed to explore lithium-decorated layered iron-based superconductors (FeX, where X=S, Se, Te).
• The study analyzed electronic structures, magnetic properties, and the influence of spin-orbit coupling (SOC).

Main Results:

• Stable 2D structures of Li-decorated FeX were identified, exhibiting room-temperature ferromagnetism.
• Large-gap, high-Chern-number QAH insulators with multiple chiral edge modes were predicted in these 2D materials.
• A 3D QAH insulator phase was also found in bulk LiOH-LiFeX.

Conclusions:

• Lithium decoration induces robust ferromagnetism and topological properties in 2D iron-based materials.
• These findings pave the way for realizing high-temperature QAH physics and novel quantum applications.
• The predicted materials offer a promising platform for exploring emergent topological phenomena at elevated temperatures.