Gate-tunable chiral spin mode in WSe2/WS2 moir\'e superlattices
Abstract
The interplay between many-body and spin-orbit effects (SOC) can lead to novel phenomena in solids. Chiral spin modes (CSM) are collective spin excitations that arise from such interplay and connect states with opposite chirality, which, however, have been rarely observed. Here, we report a gate-tunable CSM that occurs between conduction SOC-split minibands in near-0{\deg}-twisted WSe2/WS2 bilayers. This mode manifests as a sharp resonance with giant Raman efficiency in the pseudovector-symmetry channel of the Raman spectra. By varying fillings, the CSM transitions from chiral spin exciton to excitonic polaron. The spin-flip nature is directly confirmed by the Zeeman effect. Moreover, the filling dependence compellingly evidences a charge-transfer insulator at filling of one. Our results demonstrate transition-metal-dichalcogenides moir\'e superlattices as a fertile platform for exploring exotic low-lying collective excitations.
Cite
@article{arxiv.2509.16511,
title = {Gate-tunable chiral spin mode in WSe2/WS2 moir\'e superlattices},
author = {Zhexu Shan and Wenjian Su and Kenji Watanabe and Takashi Taniguchi and Shiyao Zhu and Yuanfeng Xu and Yanhao Tang},
journal= {arXiv preprint arXiv:2509.16511},
year = {2025}
}