Chiral magnons in altermagnetic RuO2

Libor Šmejkal; Alberto Marmodoro; Kyo-Hoon Ahn; Rafael Gonzalez-Hernandez; Ilja Turek; Sergiy Mankovsky; Hubert Ebert; Sunil W. D'Souza; Ondřej Šipr; Jairo Sinova; Tomas Jungwirth

arXiv · 2211.13806

Chiral magnons in altermagnetic RuO2

Libor Šmejkal·Alberto Marmodoro·Kyo-Hoon Ahn·Rafael Gonzalez-Hernandez·Ilja Turek·Sergiy Mankovsky·Hubert Ebert·Sunil W. D'Souza·Ondřej Šipr·Jairo Sinova·Tomas Jungwirth

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Abstract

Magnons in ferromagnets have one chirality, and typically are in the GHz range and have a quadratic dispersion near the zero wavevector. In contrast, magnons in antiferromagnets are commonly considered to have bands with both chiralities that are degenerate across the entire Brillouin zone, and to be in the THz range and to have a linear dispersion near the center of the Brillouin zone. Here we theoretically demonstrate a new class of magnons on a prototypical $d$-wave altermagnet RuO$_2$ with the compensated antiparallel magnetic order in the ground state. Based on density-functional-theory calculations we observe that the THz-range magnon bands in RuO$_2$ have an alternating chirality splitting, similar to the alternating spin splitting of the electronic bands, and a linear magnon dispersion near the zero wavevector. We also show that, overall, the Landau damping of this metallic altermagnet is suppressed due to the spin-split electronic structure, as compared to an artificial antiferromagnetic phase of the same RuO$_2$ crystal with spin-degenerate electronic bands and chirality-degenerate magnon bands.

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Libor Šmejkal, Alberto Marmodoro, Kyo-Hoon Ahn, Rafael Gonzalez-Hernandez, Ilja Turek, Sergiy Mankovsky, Hubert Ebert, Sunil W. D'Souza, Ondřej Šipr, Jairo Sinova, Tomas Jungwirth. 2022-11-24. Chiral magnons in altermagnetic RuO2. https://arxiv.org/abs/2211.13806

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