2025/06/06 by Jiayu David Cao, K. S. Denisov, Cao, Jiayu David +5 · 3 citations
Materials Science · Physics and Astronomy · #2D Materials and Applications #Advanced Condensed Matter Physics #FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Topological Materials and Phenomena
paper · pdf · doi:10.48550/arxiv.2506.05753
openalex publication_date 2025/06/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/29
Excitons, bound electron-holes states, often dominate the optical response of two-dimensional (2D) materials and reflect their inherent properties, including spin-orbit coupling, magnetic ordering, or band topology. By focusing on a growing class of collinear antiferromagnets with a nonrelativistic spin splitting, referred to also as altermagnets (AM), we propose a theoretical framework based on the spin space group (SSG) to elucidate their resulting excitons. Our approach is illustrated on 2D AM with spin-polarized valleys, where we classify the combination of conduction and valence bands by the SSG representations into two cases that hosts bright s-like and p-like excitons, respectively. This analysis is further supported by effective Hamiltonians and the Bethe-Salpeter equation. We identify the excitonic optical selection rules from the calculated absorption spectra and the symmetry of bright excitons from their momentum space envelope functions. Our framework provides optical fingerprints for various cases of AM, while their tunability, such as the strain-induced valley splitting, is also transferred to excitons allowing, additionally, valley-polarized photocurrent generation.