Purely magnetic field-controlled valley polarization reversal luminescence in electrically pumped TMDCs
In the study of photoluminescence spectroscopy, non-resonant excitation factors have different effects on the valley polarization properties of different TMDCs materials, which in turn limits the systematic comparative study between systems. To this end, the researchers used an electrically pumped quantum well structure combined with a pure external magnetic field (non-magnetic electrodes / substrate) to achieve efficient control and direction reversal of valley polarized electroluminescence in a variety of transition metal chalcogenides ( TMDCs ), opening up a new path for the study of optical properties of two-dimensional semiconductors and the development of valley electronics devices.
Yu Ting's research group at Wuhan University published a research article titled Electrically Pumped Valley Emitter in Transition Metal Dichalcogenides with Magnetic Manipulation in Small Methods. They used an electrically pumped quantum well structure to uniformly inject electrons / holes into the conduction band / valence band of the material through tunneling injection. The generated electroluminescence is determined by the intrinsic structure of the material, eliminating the interference of non-resonant excitation of optical pumping. The research team systematically studied the valley polarized electroluminescence of single-layer WS₂ , homogeneous bilayer ( WS₂/WS₂ ), heterogeneous bilayer ( WS₂/WSe₂ ) and single-layer MoS₂ under a perpendicular magnetic field. The key breakthrough is that the polarization direction of valley polarized electroluminescence can be reversed by simply changing the direction of the external magnetic field without the aid of magnetic electrodes or magnetic substrates.
Figure 1. Comparison between optical pumping and electric pumping, as well as valley polarization reversal of magnetically controlled electric pumping based on quantum well structure.
Figure 2. Quantum well device structure and magneto-electroluminescence properties of different systems.
The established electric pumping combined with pure magnetic field manipulation is an effective and scalable solution to achieve valley-polarized luminescence of TMDCs . It not only provides a novel research tool for in-depth understanding of two-dimensional semiconductors, especially their spin - valley physics and exciton effects, but also lays an important technical foundation for the design and development of next-generation optoelectronic devices based on valley degrees of freedom. Future research can explore the combination of this platform with moiré superlattices, fine magnetic field control or doping engineering to reveal richer physical phenomena and realize more flexible device functions.
Paper information:
Electrically Pumped Valley Emitter in Transition Metal Dichalcogenides with Magnetic Manipulation.
Yilin Liu, Haiyang Liu * , Fanglu Qin, Aosai Yang, Sheng Liu * , Li Zhang, Mengqi Zeng, Junyong Wang, Lei Fu, Ruitao Lv, Kai Zhang, Fengcheng Wu, Hao Wang, Ting Yu *
Small Methods
https://doi.org/10.1002/smtd.202500156
