Dirac Magnon Nodal Loops in Quasi-2D Quantum Magnets

Area of Science:

• Condensed Matter Physics
• Quantum Magnetism
• Topological Materials

Background:

• Quasi-2D quantum magnetic systems exhibit complex magnetic phenomena.
• Honeycomb ferromagnets, like CrX3, are promising platforms for studying exotic magnetic states.
• Understanding magnon band structures is crucial for exploring quantum properties.

Purpose of the Study:

• To propose and theoretically investigate a novel topological feature in quantum magnetic systems.
• To introduce the concept of 2D Dirac magnon nodal-line loops.
• To explore their topological protection and robustness.

Main Methods:

• Theoretical modeling of bilayer honeycomb ferromagnets.
• Analysis of magnon band structures in 2D momentum space.
• Investigation of topological protection by symmetries (inversion and time-reversal).

Main Results:

• Discovery of 1D closed lines of Dirac magnon nodes, termed "2D Dirac magnon nodal-line loops", in bilayer honeycomb ferromagnets.
• These nodal-line loops are topologically protected by inversion and time-reversal symmetry.
• The loops are robust against weak Dzyaloshinskii-Moriya interactions and exhibit chiral magnon edge modes.

Conclusions:

• The proposed 2D Dirac magnon nodal-line loops represent a new topological state in quantum magnetism.
• These findings are realizable in materials like CrX3 and other layered systems.
• The topological protection and chiral edge modes offer potential for future spintronic applications.