Symmetry design of excitons in altermagnets

Symmetry provides a powerful framework for describing physical properties and analyzing the coupling between various degrees of freedom [1-2]. With the emergence of unconventional magnets, particularly altermagnets, the tunability arising from their rich magnetoelectric coupling has garnered widespread attention [3-4]. Here, we focus on exciton properties of two-dimensional altermagnets [5]. We develop a theoretical framework based on spin space group (SSG) theory to elucidate the nature of excitons in these systems and classify the combination of conduction and valence bands according to their SSG representations. Our framework provides optical fingerprints for altermagnets and reveals how their tunability is transferred to excitons.

[1] T. Zhuo, and I. Zutic, Nat. Mater. 22, 284 (2023)

[2] Y. Liu, J. Li, P. Liu, and Q. Liu, npj Quantum Mater. 9, 69 (2024)

[3] X. Duan, J. Zhang, Z. Zhu, Y. Liu et al., Phys. Rev. Lett. 134, 106801 (2025)

[4] M. Gu, Y. Liu, H. Zhu, K. Yananose et al., Phys. Rev. Lett. 134, 106802 (2025)

[5] J. D. Cao, K. S. Denisov, Y. Liu, I. Zutic, arXiv:2506.05753 (2025)