FeTaX_{2}: A Ferrimagnetic Quantum Anomalous Hall Insulator

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Physics

Background:

• Quantum anomalous Hall insulators (QAHIs) are topological materials exhibiting dissipationless edge states.
• Discovering new QAHIs with large topological gaps and high operating temperatures is crucial for practical applications.

Purpose of the Study:

• To propose a new family of van der Waals layered ternary transition metal chalcogenides, FeTaX_{2} (X=S, Se, Te), as potential ferrimagnetic quantum anomalous Hall insulators.
• To investigate the origin of magnetic order and the mechanism for the large topological gap in these materials.

Main Methods:

• First-principles calculations were employed to study the electronic and magnetic properties of FeTaX_{2} monolayers.
• Band structure analysis was performed to identify band inversion and calculate the topological invariants.

Main Results:

• FeTaX_{2} compounds were identified as ferrimagnetic QAH insulators with a sizable bulk gap and a high Chern number (C=-2).
• The magnetic order is primarily driven by Fe atoms, inducing moments on Ta sites.
• A unique s-d-type band inversion involving Ta d_{z^{2}} and d_{xy} orbitals near the Fermi level is responsible for the large topological gap.
• Predicted Curie temperatures for monolayer FeTaX_{2} significantly exceed that of monolayer MnBi_{2}Te_{4}.

Conclusions:

• FeTaX_{2} represents a promising new class of materials for realizing the quantum anomalous Hall effect.
• The tunable Curie temperature and topological gap, dependent on spin-orbit coupling, offer pathways for novel spintronic and quantum computing devices.
• Experimental realization of these materials could advance the field of topological quantum physics.