Generic Approach to Intrinsic Magnetic Second-Order Topological Insulators via Inverted p-d Orbitals.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Two-dimensional (2D) materials with intrinsic magnetism and non-trivial topology are key for exotic quantum phenomena.
• The development of intrinsic magnetic second-order topological insulators (SOTIs) is significantly less explored than their nonmagnetic counterparts.
• Existing research on topological materials often overlooks the crucial role of orbital inversion.

Purpose of the Study:

• To address the limited pursuit of intrinsic magnetic SOTIs by investigating the phenomenon of p-d orbital inversion.
• To establish a theoretical framework for understanding and utilizing p-d orbital inversion in designing topological materials.
• To identify real-world material candidates exhibiting intrinsic ferromagnetism and SOTI properties.

Main Methods:

• Development of a theoretical framework combining density-functional theory (DFT) calculations and Wannier downfolding.
• Elucidation of the p-d orbital inversion mechanism through theoretical modeling.
• Identification and characterization of candidate materials using computational methods.

Main Results:

• Successfully established a theoretical framework for understanding p-d orbital inversion in topological materials.
• Identified two distinct real materials, 1T-VS2 monolayer (hexagonal lattice) and CrAs monolayer (square lattice), as intrinsic ferromagnetism SOTIs.
• Demonstrated the generality of the p-d orbital inversion concept across different lattice structures.

Conclusions:

• The p-d orbital inversion mechanism offers a generic and effective pathway for realizing intrinsic magnetic SOTIs.
• This work expands the scope of known magnetic topological materials and provides a new design principle.
• Findings pave the way for future exploration of novel quantum anomalous Hall insulators and magnetic topological phases.