Competing Magnetic Interactions in the Antiferromagnetic Topological Insulator MnBi_{2}Te_{4}

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• MnBi2Te4 is a candidate for the first antiferromagnetic (AFM) topological insulator.
• Understanding its magnetic interactions is crucial for exploring its quantum properties.

Purpose of the Study:

• To investigate the magnetic interactions within MnBi2Te4.
• To characterize the spin wave excitations and exchange interactions.

Main Methods:

• Inelastic neutron scattering was employed to study the magnetic interactions.
• Analysis of spin waves provided insights into the magnetic structure.

Main Results:

• Ferromagnetic triangular layers with AFM interlayer coupling were identified.
• A large spin gap was observed in the spin waves.
• Long-ranged and frustrated pairwise exchange interactions were characterized, with significant next-nearest neighbor AFM exchange.

Conclusions:

• The magnetic frustration in MnBi2Te4 suggests proximity to various magnetic phases.
• Potential for accessing skyrmion phases through chemical tuning or applied fields was highlighted.