Chiral Magnons in Altermagnetic RuO_{2}

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Magnons in ferromagnets typically exhibit single chirality and GHz frequencies with quadratic dispersion.
• Antiferromagnetic magnons are generally considered to have degenerate bands of both chiralities, THz frequencies, and linear dispersion.

Purpose of the Study:

• To theoretically demonstrate a new class of magnons in a d-wave altermagnet.
• To investigate the properties of magnons in RuO2 with compensated antiparallel magnetic order.

Main Methods:

• Density-functional-theory (DFT) calculations were employed.
• Analysis of magnon bands and their dispersion relations.
• Comparison with an artificial antiferromagnetic phase of RuO2.

Main Results:

• Observation of THz-range magnon bands in RuO2 with alternating chirality splitting.
• Demonstration of linear magnon dispersion near the zero wave vector.
• Suppressed Landau damping in the metallic altermagnet due to spin-split electronic structure.

Conclusions:

• RuO2 hosts a novel class of magnons with alternating chirality.
• The spin-split electronic structure in altermagnets can suppress Landau damping.
• These findings open new avenues for spintronic applications utilizing altermagnets.