Probing the Néel-Type Antiferromagnetic Order and Coherent Magnon-Exciton Coupling in van der Waals VPS 3 .

Two-dimensional (2D) van der Waals (vdW) antiferromagnets have received intensive attention due to their terahertz resonance, multilevel magnetic-order states, and ultrafast spin dynamics. However, accurately identifying their magnetic configuration still remains a challenge owing to the lack of net magnetization and insensitivity to external fields. Herein, we experimentally probe the Néel-type antiferromagnetic (AFM) order in 2D antiferromagnet VPS 3 with the out-of-plane anisotropy, which is demonstrated by the temperature-dependent spin-phonon coupling and second harmonic generation (SHG). This long-range AFM order even persists at the ultrathin limit. Furthermore, the strong interlayer exciton-magnon coupling (EMC) upon the Néel-type AFM order is detected based on monolayer WSe 2 /VPS 3 heterostructure, which induces an enhanced excitonic state and further certifies the Néel-type AFM order of VPS 3 . Our discovery provides optical routes as the novel platform to study 2D antiferromagnets and promotes their potential applications in magneto-optics and opto-spintronic devices. This article is protected by copyright. All rights reserved.