Robust circular polarization of indirect Q-K transitions in bilayer 3R-W S2

Research output: Contribution to journalArticleScientificpeer-review


  • Luojun Du
  • Qian Zhang
  • Tingting Zhang
  • Zhiyan Jia
  • Jing Liang
  • Gui Bin Liu
  • Rong Yang
  • Dongxia Shi
  • Jianyong Xiang
  • Kaihui Liu
  • Zhipei Sun
  • Yugui Yao
  • Qingming Zhang
  • Guangyu Zhang

Research units

  • Chinese Academy of Sciences
  • Renmin University of China
  • Beijing Institute of Technology
  • Yanshan University
  • Peking University
  • Lanzhou University
  • University of Chinese Academy of Sciences
  • Songshan Lake Materials Laboratory


Valley-contrasting Berry curvature and orbital magnetic moment have led to highly selective circular polarization of direct excitons at the K valleys in transition-metal dichalcogenides. In addition to K valleys, Q valleys, another critical point in the conduction band, also possess well-defined but distinct magnetic moment. Being akin to the direct excitons at K valleys, indirect excitons associated with Q (K) valleys in the conduction (valence) band could allow circular polarization in principle. Here, we report an experimental observation of the circular polarization of indirect Q-K transitions in noncentrosymmetric bilayer 3R-WS2. In stark contrast to the circular polarization of direct excitons which depolarizes with increasing lattice temperature, the circular polarization of indirect Q-K excitons is extremely robust and independent on the temperature. Such robust circular polarization can be understood as follows: The spin-orbit coupling in the Q valley is much stronger than that in the K point of the conduction band, significantly suppressing the temperature induced valley depolarization. Our results open up opportunities for exotic valleytronics and quantum information processing applications.


Original languageEnglish
Article number161404
JournalPhysical Review B
Issue number16
Publication statusPublished - 23 Oct 2019
MoE publication typeA1 Journal article-refereed

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