Quantum interference between dark-excitons and zone-edged acoustic phonons in few-layer WS₂

• Main Authors: Tan, Qinghai, Li, Yun-Mei, Lai, Jia-Min, Sun, Yu-Jia, Zhang, Zhe, Song, Feilong, Robert, Cedric, Marie, Xavier, Gao, Weibo, Tan, Ping-Heng, Zhang, Jun
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2023
• Subjects: Science::Physics; Photoluminescence; Raman Spectrometry
• Online Access: https://hdl.handle.net/10356/169751
• Institution: Nanyang Technological University

Fano resonance which describes a quantum interference between continuum and discrete states, provides a unique method for studying strongly interacting physics. Here, we report a Fano resonance between dark excitons and zone-edged acoustic phonons in few-layer WS2 by using the resonant Raman technique. The discrete phonons with large momentum at the M-point of the Brillouin zone and the continuum dark exciton states related to the optically forbidden transition at K and Q valleys are coupled by the exciton-phonon interactions. We observe rich Fano resonance behaviors across layers and modes defined by an asymmetry-parameter q: including constructive interference with two mirrored asymmetry Fano peaks (weak coupling, q > 1 and q < - 1), and destructive interference with Fano dip (strong coupling, ∣q∣ < < 1). Our results provide new insight into the exciton-phonon quantum interference in two-dimensional semiconductors, where such interferences play a key role in their transport, optical, and thermodynamic properties.